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15 June 2025, Volume 43 Issue 3
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    Test and Research
  • Prediction of thermal deformation mechanical properties and simulation analysis of microstructure evolution for 316L steel
    QU Kejie, SUN Hao, TU Yekuan, SHA Jinyang, YANG Qingzhao, ZHANG Zhen
    2025, 43(3): 1-9. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240089
    Abstract ( 34 ) Download PDF ( 0 )   Knowledge map   Save
    To provide numerical solutions for optimizing thermal deformation process parameters, and break through the efficiency bottleneck of traditional trial-and-error method in high temperature plastic forming quality control, thermal simulation testing machine was used to conduct thermal simulation compression tests on 316L austenitic steel at different strain rates. The local mechanical response of grains under different thermal deformation conditions was investigated by nanoindentation test, and the recrystallization process of thermal deformation was analyzed by DEFORM finite element simulation software. A genetic algorithm(GA) back propagation (BP) artificial neural network (ANN) with nonlinear mapping capability was used to predict the mechanical properties of austenitic steel. The results showed that the dynamic recrystallization was the dominant mechanism of microstructure evolution in thermal compression deformation process of 316L austenitic steel, and its progress was significantly affected by strain rate. The tests indicated that the recrystallization nucleation and grain reconstruction could be effectively promoted by high strain rate via accelerating dislocation multiplication and energy accumulation. The numerical simulation study further demonstrated that the dynamic recrystallization volume fraction of materials showed positive growth with the increase of deformation amount, which was accompanied by remarkable grain refinement effect. The high temperature rheological behavior of the material was predicted. The hybrid intelligent algorithm model based on genetic algorithm optimization was proposed. The stability of accuracy of stress prediction was greatly improved by modifying the initial parameter sensitivity of BP neural network, which provided reliable calculation method for numerical simulation of complex thermal deformation process.
  • Effect of tensile average stress on multi-axial loading fatigue failure of Q345 steel for metallurgical crane main beam
    LI Fei, CAO Xia, LUO Zhenkun, YANG Binjun, LIU Hao, LI Hao
    2025, 43(3): 10-18. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240040
    Abstract ( 31 ) Download PDF ( 0 )   Knowledge map   Save
    Fatigue life is one of the important indexes for safety assessment of crane, and the existence of average stress is one of important factors to be considered in multi-axial fatigue failure of Q345 steel for metallurgical crane main beam. Uniaxial tension-compression and pure torsion fatigue tests were conducted on the main material Q345 steel for metallurgical crane main beam, and the tensile stress(S)-fatigue life (N) curves and torsional stress S-N curves of the material were obtained. Based on the test results, an appropriate stress was selected as the equivalent stress for multi-axial fatigue loading, and the multi-axial fatigue fatigue tests with different average tensile stresses were carried out under this equivalent stress.The variations of the maximum normal stress and the maximum shear stress under different tensile average stresses and their corresponding planar directions were theoretically deduced. The initiation and propagation of cracks on the surface of fatigue specimen were observed by optical microscope, and the microscopic morphological characteristics of specimen fracture surface were analyzed by scanning electron microscope (SEM) to investigate the failure modes of Q345 steel under different tensile average stresses. The research showed that the multi-axial fatigue life of Q345 steel would be significantly reduced with the influence of tensile average stress. With the increase of tensile average stress, the shear stress gradually played a dominant role in the process of fatigue failure.
  • Effect of heat treatment on microstructure of 70Cr5Mo steel used for cold rolling roller
    LAN Yong, LIU Shuai, CUI Haifeng, CHEN Xu
    2025, 43(3): 19-26. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240066
    Abstract ( 24 ) Download PDF ( 0 )   Knowledge map   Save
    Grass-like wave problem is a common surface wave defect in forged steel cold rolling roller billets. If the traditional tempering and surface hardening processes are adopted, the problem of surface wave defect in the finished rolling roller products cannot be effectively eliminated. The post-forming heat treatment processes such as normalizing and spheroidizing annealing were employed to reduce or eliminate the grass-like wave defects that occured during ultrasonic testing of 70Cr5Mo steel roller billet products. The results showed that a uniform and fine spheroidized pearlite structure could be obtained by adopting a combined pre-treatment process of normalizing with isothermal spheroidizing annealing, effectively improving the microstructure of 70Cr5Mo steel, thereby achieving the goal of reducing or eliminating the grass-like waves.The recommended process was as follows: normalizing (holding at 1 070 ℃ for a certain period and then air cooling) →isothermal spheroidization (holding at 970 ℃)→rapid cooling to 770 ℃ and holding for a certain period→furnace cooling to 500 ℃ and then unloading for air cooling.
  • Discussion on impact sampling method of thin-walled austenitic stainless steel seamless pipe
    CAO Xinming, CHEN Fanhu, XIE Yi, XING Feifei
    2025, 43(3): 27-30. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240065
    Abstract ( 15 ) Download PDF ( 0 )   Knowledge map   Save
    The surface removal amount of impact specimens is specified in ASTM A 370-2022, and it is in contradiction with ASME B31.3-2022 where the overcooling degree should be considered when the notch width of the notched specimens is less than 80% of material thickness. Based on this, an impact sampling method of thin-walled austenitic stainless steel seamless tubes was discussed. Impact tests were compared on austenitic stainless steel seamless tube specimens in original (solution) state and flattened state respectively, and the results showed that the impact absorbed energy in flattened state was significantly greater than that in original state. Hardness comparison tests were conducted at three different positions on the same flattened state specimens, namely the end, 1/4 (width) W and 1/2 W. The results indicated that the hardness at 1/4 W of specimen was the lowest. The ferrite numbers of specimens in original state and flattened state were determined respectively. The results indicated that the ferrite number in flattened state was significantly higher than that in original state. At 1/4 W of specimen, hardness tests were compared in flattened state and original state under both room temperature and -196 ℃ conditions. The results showed that the hardness of specimen in flattened state at both room temperature and -196 ℃ were higher than those in original state. The strain hardening in flattening process played a dominant role at -196 ℃, which was the main reason for the above phenomena. Therefore, it was considered that the surface removal amount specified in ASTM A370 could be neglected for thin-walled austenitic stainless steel seamless pipes, and the results of impact tests were more representative when the specimens were directly sampled in original state. Meanwhile, it could also meet the requirements for the degree of undercooling specified in ASME B31.3-2022.
  • Discussion on test method for axial tensile stress corrosion
    YUAN Shaohong, SONG Wencheng, WANG Jun, ZHANG Hongjing, SHI Dandan, XU Sheng
    2025, 43(3): 31-36. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240044
    Abstract ( 15 ) Download PDF ( 0 )   Knowledge map   Save
    To investigate and replenish stress corrosion criteria, the axial tensile stress corrosion tests of 2026-T3511 aluminum alloy in the transverse direction were comprehensively analyzed by axial specimen fracture macrostructure observation, metallographic microstructure observation, fracture scanning and blank microstructure verification. It was found that it belonged to stress corrosion failure even if the axial tensile specimen was broken beyond the standard distance. By the short-transverse C ring stress corrosion test, it was found that when conducting axial tensile stress corrosion tests, if the material exhibited transgranular fracture perpendicular to specimen axis and secondary crack parallel to specimen axis, namely intergranular crack, they could also be used as the criterion for stress corrosion failure.In order to verify the influence of specimen length, exposure length and processing parameters on test results, the control variable method was adopted. It was found that the greater the specimen length and exposure length, the lower the finish turning speed, and the less effect on stress corrosion. The surface residual stress caused by rough turning feed in the standard procedure could be ignored.
  • Determination of equivalent coefficient of digital radiography for boron carbide bullet-resistant ceramic and aluminum alloy
    ZHU Guifeng, ZANG Lili, LI Shuai, JIAO Zhongbin, WANG Yan, MENG Quansheng
    2025, 43(3): 37-41. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240045
    Abstract ( 14 ) Download PDF ( 0 )   Knowledge map   Save
    Boron carbide ceramic is a kind of bullet-resistant material. In order to ensure its protective performance, it is necessary to strictly control its quality through non-destructive testing methods. At present, X-ray method is commonly used for its internal quality inspection.While, the determination of its exposure conditions is lack of corresponding basis during detection by X-ray digital radiography (DR). Under the same transparent tube voltage, X-ray digital radiography of boron carbide bullet-resistant ceramic multistep test blocks and 6063 aluminum alloy multistep test blocks were carried out by equivalent coefficient method, providing a basis for determination of its exposure conditions. The results showed that the equivalent coefficient of boron carbide bullet-resistant ceramic and 6063 aluminum alloy was 0.71-0.86 when the transparent tube voltage was 45-70 kV. The test results had a certain guiding significance for the determination of X-ray digital radiography conditions for boron carbide bullet-resistant ceramic.
  • Preparation of thorium dioxide pellet metallographic sample
    DU Yanhua, GUO Hong, CHI Chunxia, HE Jinming
    2025, 43(3): 42-46. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240053
    Abstract ( 12 ) Download PDF ( 0 )   Knowledge map   Save
    The development of preparation method for metallographic samples of thorium dioxide nuclear fuel pellets is of great significance for its microstructure observation and performance study. The influences of five types of chemical etchants, including H2SO4, HCl-H2O, H2SO4-HNO3-HCl-H2O, H2SO4-HCl-H2O and H3PO4 on the preparation of thorium dioxide pellet metallographic sample were investigated to optimize the chemical etching method. The effects of different molding pressure conditions on microscopic pore, cracking and grain size of metallographic samples were discussed. The results demonstrated that the clear grain boundaries could be observed only by preparation with two etchants, i.e., H2SO4-HCl-H2O and H3PO4. Considering the relatively weaker irritating odor of H3PO4, it was selected for etch preparation of thorium dioxide pellet metallographic sample. Under identical molding pressure, the raw powder with higher specific surface area was more helpful for the reduction of pores and cracks as well as the growth of grains in thorium dioxide pellet due to the superior sintering driving force and sintering activity.
    • Defect Analysis
  • Formation mechanism of edge peeling defect in hot-rolled steel strip
    YANG Yingying, JIAO Huili, LI Yi, CUI Erbao, TIAN Le, HUO Guangfan
    2025, 43(3): 47-52. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240063
    Abstract ( 14 ) Download PDF ( 0 )   Knowledge map   Save
    The edge peeling defect on surface of hot-rolled steel strip is a bottleneck problem to restrict the improvement of its surface quality. Aiming at the edge peeling defect in hot-rolled steel strip, the microstructure and chemical composition of the defect areas were analyzed by scanning electron microscopy(SEM) and energy dispersive spectrometer(EDS). Moreover, the statistical analysis of production data and the rolling test of flame-cleaning slab with prefabricated defect with were conducted in 2 250 mm hot continuous rolling line of Qian'an Iron and Steel Company of Beijing Shougang Co., Ltd., and the causes and evolution process of edge peeling defect in steel strip were clarified. The results showed that the accumulation and residual of slag convergence ridge caused by poor flame cleaning quality of cast slab could not be completely removed after heating in reheating furnace and descaling by descaler. The residual oxide layers from slag convergence ridge were partially embedded into the steel substrate during rough rolling and finish rolling while others remained on the surface of steel strip, ultimately forming edge peeling defect containing numerous oxidized spots with maximum thickness up to 150 μm. An industrial experiment was conducted to investigate the impact of edge convergence ridges removal by flame for slab on the quality of the hot rolled edge. Subsequently, process optimization was carried out and production data were continuously tracked. The results demonstrated that the improvement of flame cleaning quality to reduce the occurrence of intersection edge or the use of narrow-side non-cleaning process could reduce the incidence of edge peeling defect by 87%.
  • Fracture analysis of 25Mn cold-drawn steel pipe during straightening
    LIU Junli, ZHENG Dongwei, LI Songtao
    2025, 43(3): 53-57. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240046
    Abstract ( 27 ) Download PDF ( 0 )   Knowledge map   Save
    25Mn hot rolled seamless steel tubes were used to manufacture cold-drawn steel tubes for hydraulic cylinder in a factory. Some steel tubes had transverse fractures in the straightening process, which greatly affected the production organization and resulted in great loss. The on-site investigation and sampling were conducted. The physical and chemical tests, including chemical composition, mechanical properties, metallographic structure, scanning electron microscope fracture analysis, on the fractured steel pipes and hot rolled steel pipes of the same batch were also performed. The reasons for the transverse fracture of 25Mn steel pipes in the straightening process after cold-drawing were analyzed. It was confirmed through the tests that the primary failure mode of transverse fracture of steel pipe in the straightening process was the damage to inner wall of pipe due to poor lubrication in the cold drawing process. The secondary failure mode was poor lubrication due to the poor quality of phosphorization-saponification treatment before cold-drawing, with insufficient and uneven film thickness. The tertiary failure mode was the uncontrolled process of phosphorization-saponification procedure. There were two main reasons for the loss of process control:first, the temperature and time for phosphorization were controlled arbitrarily; second, the amount of steel added is large, resulting in a high degree of contamination of bath.
  • Fracture reason analysis of 45 steel motor shaft
    SUN Yuhong, ZHU Shili, LI Jiaxin, LI Mingsong, REN Changchun, WANG Ye
    2025, 43(3): 58-62. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240057
    Abstract ( 16 ) Download PDF ( 0 )   Knowledge map   Save
    The macroscopic observation and microstructure analysis of fracture of 45 steel motor shaft were conducted by metallographic microscope, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The fracture reasons were comprehensively analyzed based on the chemical composition, hardness testing and metallographic morphology. The results showed that the chemical composition of the motor shaft met the composition requirements of 45 steel specified in GB/T 699-2015. Based on hardness test results and analysis of macroscopic structure morphology, it could be concluded that the motor shaft has undergone quenching and tempering in some areas. The short-term fracture was due to the presence of numerous granular non-metallic inclusions and holes within the motor shaft material. At the fracture surface, there was a depression with a diameter of approximately 3.4 mm near the edge. During the operation of the motor, it caused stress concentration, forming a crack source, and then the cracks extended towards the edge. Due to the presence of numerous inclusions and holes within the material, which made it overall loose, the cracks spread rapidly, resulting in the short-term fracture of the motor shaft.
  • Failure analysis of abnormal leakage of tin bronze pressure reducing valve parts
    HUANG Lin, WANG Zhenzhong, LI Zhihao, WANG Shining, YANG Yuntao
    2025, 43(3): 63-67. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240064
    Abstract ( 12 ) Download PDF ( 0 )   Knowledge map   Save
    A certain equipment, equipped with a cast tin bronze pressure reducing valve parts (QSn4-4-2.5), experienced a failure phenomenon of perforation and leakage after being in use for some time. The leakage causes of the pressure reducing valve parts were analyzed by inductively coupled plasma optical emission spectrometer (ICP-OES), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results showed that the chemical composition of material for the failed pressure reducing valve parts could meet the technical requirements of relevant standards, and no obvious abnormality was found in the metallographic structure. The perforation and leakage of the pressure reducing valve parts were caused by local corrosion inside the valve body. The erosion corrosion by seawater was the main cause of local corrosion leakage, and the presence of micro-porosity in the material could accelerate the generation and expansion of corrosion.
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  • Analysis of influencing factors on measurement accuracy of surface Rockwell hardness of tinplate
    YUAN Xiaoqian, WANG Wei, HOU Yongliang, SUN Jing, YANG Yuqian
    Physics Examination and Testing. 2025, 43(1): 6-9. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240018
    Abstract (492) Download PDF (4)   Knowledge map   Save
    The surface Rockwell hardness of tinplate could reflect the tinplate hardness of its surface. This feature is very important for the processing and application of tinplate. Therefore, the surface Rockwell hardness measurement is an important step in the inspection process of tinplate. The method for measuring the surface Rockwell hardness is similar to the ordinary Rockwell hardness, but the applied load is different. HR 30T and HR 15T steel balls were used as indenter, and the head diameter was Φ1.587 5 mm. Under the conditions of total load composed of initial test force and main test force, the steel balls were pressed onto the sample surface. The pressure was maintained in the specified time. Then the main test force was removed, while the initial load was still maintained. The indentation residual depth caused by main test force was measured to calculate the surface Rockwell hardness value.
  • Progress of material characterization techniques based on neutron Bragg-edge transmission imaging
    WANG Yangwen, XU Pingguang, SU Yuhua, MA Yanling, WANG Honghong
    PHYSICS EXAMINATION AND TESTING. 2024, 42(4): 32-41. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230085
    Abstract (126) Download PDF (75)   Knowledge map   Save
    With the rapid development of spallation neutron source large-scale scientific facility technologies, the neutron beam flux that can be obtained has been significantly enhanced, and the neutron imaging technique has been also further developed. Due to the limitation of neutron beam flux, the conventional neutron imaging techniques require neutron beam with wide wavelength range to obtain relatively high flux conditions. In recent years, the high-flux pulsed neutron beam has been obtained via the large accelerator spallation neutron source. The energy (wavelength) resolved neutron imaging technique based on Bragg-edge effect, i.e., neutron Bragg-edge transmission imaging technology, has showed a wide application potential due to its high energy resolution, high spatial resolution and the ability to detect the crystallographic information. The fundamental principle of this technology was briefly introduced. Some application cases in residual strain, phase composition, dislocation density and oriented structure characterization were reviewed to play a positive role in the popularization of relevant techniques.
  • Determination of specific heat capacity and Curie temperature of NdFeB by differential scanning calorimetry
    XIA Yumei, LI Xinxin, NIE Chenghong, JIA Xiaoqi, REN Xudong, LI Quan
    Physics Examination and Testing. 2024, 42(6): 1-5. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240007
    Abstract (93) Download PDF (0)   Knowledge map   Save
    The specific heat capacity of NdFeB material was determined by differential scanning calorimetry (DSC) method. The optimal test conditions were explored from the aspects of crucible selection, standard sample mass and sample weight. Meanwhile, the Curie temperature of NdFeB material was determined by the abnormal turning point of the specific heat capacity near the Curie temperature. The optimal testing conditions were obtained as below: the aluminum (Al) crucible was selected; the mass of sapphire standard sample was 43.3 mg; the sample weight was about 43.3 mg. The results showed that the Curie temperature (TC) of NdFeB material determined by DSC was consistent with that of typical NdFeB magnetic steel (310 ℃). The Curie temperature of NdFeB materials with different grades was in range of 290-330 ℃, and the Curie temperature of NdFeB magnetic material obtained by this method was in the range of 243-386 ℃ of the third generation of rare earth permanent magnet materials R2Fe14B series compounds.
  • Analysis of testing methods for nonmetallic inclusions in steel in DIN 50602-1985
    WANG Yu, CHENG Lijie, QU Xiaogang, NIU Wei
    Physics Examination and Testing. 2025, 43(2): 53-57. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240032
    Abstract (86)   Knowledge map   Save
    The rating spectrum classification, inclusion classification, and evaluation methods of German standard DIN 50602-1985 of High magnification metallographic examination of nonmetallic inclusions in special steels were analyzed. Moreover, it was compared with GB/T 10561-2023 and ASTM E45-2018a which were widely used in China at present. K method in DIN 50602-1985 was more comprehensive and accurate in reflecting the level of inclusions compared with GB/T 10561 and ASTM E45 due to its more classifications of rating spectra and the use of comprehensive indices to reflect the overall hazard level of inclusions. The analysis of standard was helpful to inspectors for correct rating.
  • Analysis of crack defects in 40CrNiMoA ring forging
    GONG Yangdao, LIU Xiaolei, CHEN Changhua
    Physics Examination and Testing. 2024, 42(6): 57-61. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240013
    Abstract (84) Download PDF (5)   Knowledge map   Save
    The 40CrNiMoA alloy steel billet produced by a certain forging factory was forged into wear-resistant plate ring billet by forging hammer. After quenching and tempering heat treatment, it was found that there were many crack defects on the surface of the ring forgings. In order to investigate the causes of surface crack defects in 40CrNiMoA ring forgings, samples were dissected and analyzed for chemical composition, metallographic examination and scanning electron microscopy. The analysis results indicate that the crack in the 40CrNiMoA ring forging originates from the end face of the ring forging, and the crack propagation mode is a single transgranular propagation. The formation of the crack belongs to the stress crack of heat treatment quenching.
  • Application of UV-A lamps in penetrant testing
    SHEN Haihong, XU Lei, WAN Ce, XIA Peng, ZHOU Xiangqi, ZHANG Yubin
    Physics Examination and Testing. 2024, 42(6): 20-22. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230071
    Abstract (84) Download PDF (4)   Knowledge map   Save
    The application of LED UV-A lamp is more and more common. Its performance indicators are quite different from the high-pressure mercury vapor arc lamp, and the improper application will directly lead to the missing inspection of defects. Based on the performance index of the UV-A lamp, its use characteristics were discussed so as to facilitate the correct use of the UV-A lamp by technicians. The contents included the production certificate of the UV-A lamp, the integrity and cleanliness of the filter and the inspection method, the radiation intensity of the UV-A lamp, the leakage of the white light of the UV-A lamp, the minimum working distance, the effectiveness of the LED lamp bead work. The requirements and test methods of the UV-A lamp were analyzed in details in order to guide the inspectors to correctly grasp its use characteristics and test requirements. This study was conducive to the correct implementation of the detection, which could ensure the reliability of the defect detection results.
  • Research progress on defect detection and assessment technology for additive manufacturing
    SHI Liang, WANG Juntao, WANG Chiquan, SHAO Chengwei
    GAO Mu, FAN Yansheng, ZHANG Zitang
    Physics Examination and Testing. 2025, 43(1): 34-39. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240006
    Abstract (81) Download PDF (5)   Knowledge map   Save
    The technologies for defect assessment of additive manufacturing were investigated. The comprehensive analysis was conducted from the aspects of additive manufacturing process principles, typical defect types, defect detection, and defect assessment progress. The causes of defects and the current main non-destructive detection methods were emphatically discussed. The main defect assessment methods and research status at home and abroad were summarized and sorted out. The existing problems of additive manufacturing defect assessment technology were proposed, which could provide the reference for the assessment research of additive manufacturing defects.
  • Vickers hardness test of nickel-based single crystal superalloy
    TENG Yuefei, JIN Yi, LIN Xia, LEI Xiaojiao
    Physics Examination and Testing. 2024, 42(5): 1-5. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230090
    Abstract (79) Download PDF (49)   Knowledge map   Save
    The effects of testing forces, indentation diagonal direction, and indentation location on the measurement results of Vickers hardness for nickel-based single crystal superalloy were investigated. The results indicated that the testing force and the indentation location (either at dendrite arm or in interdendritic region) had little influence on the Vickers hardness measurement results, while the indentation diagonal direction had a certain impact. On the {100} crystal plane, the hardness value was the highest when the indentation diagonal direction lied along the <001> crystal orientation, and the lowest along the <011> crystal orientation. The difference was about 35HV. On the {111} crystal plane, the hardness value was between the above maximum and minimum values. The nickel-based single crystal superalloy exhibited anisotropy so that there were significant differences in the elastic modulus and other factors on different crystal orientations, which affected the measurement results of Vickers hardness.
  • Comparative study of phased array ultrasonic detection of water immersion and contact method
    CHEN Jile, LU Jinliang, LIU Xi, LIANG Suhua, FENG Shuting, GUAN Chu
    Physics Examination and Testing. 2024, 42(6): 6-9. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240011
    Abstract (77) Download PDF (0)   Knowledge map   Save
    In the practical application of phased array ultrasonic testing technology, the coupling methods of probe and workpieces mainly include contact method and water immersion method. In the contact detection method, the probe is in direct contact with the workpiece, and the detection effect is affected by the workpiece surface roughness and near field region. For the water immersion method, there is a water layer between the probe and the workpiece, which not only has good coupling effect, but also has no near-field influence, so the detection effect is good. This paper analyzed the defect imaging characteristics of the two detection methods, and verified the imaging effect of the same defect through comparative experiments. It showed that the water immersion method of phased array ultrasonic detection had better defect display effect and higher signal-to-noise ratio than the contact method.
  • Analysis of Rockwell hardness proficiency testing for metal materials
    BEN Jincui, YANG Junhong, ZHANG Bing, ZHANG Yixin, YU Zeli, CAO Xiaogang
    Physics Examination and Testing. 2024, 42(5): 50-57. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230119
    Abstract (75) Download PDF (40)   Knowledge map   Save
    In order to assess the laboratory's detection ability in Rockwell hardness of metal materials, a proficiency testing was conducted. Firstly, the samples were sent to the China Institute of Metrology for verification. Then, the metallographic microscopic analysis and hardness testing were conducted at different positions. It was proved that the quartering cutting did not affect the hardness value of the sample. Moreover, the uniformity and stability were good. The difference method was used for proficiency testing evaluation of the laboratory using the maximum allowable value of hardness block uniformity as the reference value. The satisfaction rates for 9 A-scale, 10 B-scale, and 15 C-scale participating laboratories using this method were 33.3%, 50%, and 53.3%, respectively, which were significantly lower compared to other evaluation principles. It demonstrated that employing this evaluation principle could identify the potential issues in the laboratory and assist in enhancing its testing capabilities. Finally, a detailed technical analysis was conducted on the results of this proficiency testing. It was concluded that the hardness tester and personnel operation were the primary factors that affected the experimental results. This analysis provided effective improvement measures and basis for laboratories with issues in proficiency testing.
  • Discussion on static Poisson's ratio testing technology at elevated temperature
    ZHANG Zhiwei, HE Xin, YUAN Ke, LEI Ming, LIU Lanzhou, CAO Yongxu
    Physics Examination and Testing. 2024, 42(6): 10-14. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240003
    Abstract (67) Download PDF (5)   Knowledge map   Save
    This article mainly introduced a high-temperature static Poisson's ratio test method using mechanical axial and transverse extensometers through axial tension. Compared to traditional high-temperature static Poisson's ratio measurement methods, the proposed method had the advantages of more convenient, low-cost, and intuitive displacement measurement. The static Poisson's ratio tests of various materials were conducted at room and high temperatures. Moreover, the data were compared with dynamic Poisson's ratio data under the same conditions. The results showed that for GH49, 316L, GH4720Li, and K6509 materials, there is a certain numerical difference between high-temperature dynamic Poisson's ratio and static Poisson's ratio, and even under temperature changes, the trend of change does not show correlation.
  • Construction practice of low magnification inspection system for continuous casting billets
    QIU Xianghua, WANG Xuelong, MA Xiaoxu, TAO Aili, MAO Weigen, HAN Xiaofei
    Physics Examination and Testing. 2024, 42(5): 58-62. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230097
    Abstract (63) Download PDF (40)   Knowledge map   Save
    In order to fully play the role of low magnification inspection in quality control of continuous casting billets, each process of low magnification inspection was studied. A low magnification laboratory that met the requirements of the management system was redesigned. The automatic low magnification inspection process was formulated. The low magnification inspection processes were designed, including the sample processing and transportation, acid etching process, scanning imaging process, and environmental protection process. The suggestions for the overall layout of the process, civil engineering, materials, and laboratory management involved in the construction of the low magnification laboratory were proposed, which provided reference for the physical inspection quality management personnel and low magnification laboratory design and construction personnel in steel enterprises.
  • Analysis of phases in superalloy and high-strength steel by combination of EDS and EBSD
    TANG Kaiming, WANG Bo, NING Xinwei, WANG Wei, ZHU Jie, XU Zhonghua
    Physics Examination and Testing. 2024, 42(5): 10-13. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230118
    Abstract (62) Download PDF (45)   Knowledge map   Save
    In order to analyze the phases of superalloy and high-strength steel, the combination method of EDS and EBSD was adopted. The non-metallic inclusions in nickel-based master alloy were identified, and the oxide layer phases of 300M low-alloy high-strength steel were distinguished. The result showed that the mean angular deviation (MAD) of the center line inclination of the nickel-based master alloy Kikuchi band was 0.79°. The non-metallic inclusion was identified as Al2O3 by comparison with the simulation bands of selected phases in the database. After ion polishing, the phases in the 300M steel oxide layer and their distribution could be distinguished and determined by the EBSD technology. Most phases were Fe3O4 followed by Fe2O3, and the content of FeO was extremely low.
  • Analysis of cold bending fracture of NM500 steel plate
    CHEN Yihui, ZENG Zhizhong, LI Jiandong, WANG Shiru, LIN Senming
    PHYSICS EXAMINATION AND TESTING. 2024, 42(4): 53-59. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230094
    Abstract (62) Download PDF (49)   Knowledge map   Save
    Fracture occurred for a 10 mm NM500 steel plate in the cold bending test process. In order to study the cause of fracture, the bending test fracture steel plate and qualified steel plate were used for comprehensive analysis including cold bending process parameters, tensile properties, microstructure and inclusions type, fracture morphology, and energy spectrum detection comparison. The results showed that the large size MnS inclusions and agglomerated TiN inclusions with irregular morphology destroyed the continuity of the steel plate, and the micro-cracks appeared in the cold bending process. With the increase of stress, the micro-cracks expanded and finally led to cold bending fracture of the steel plate.
  • Effect of acidic sulfolane solution on corrosion behavior of Q235B carbon steel
    SUN Mingdao, LI Junjun, YAN Tao, SONG Wenjing, QIN Feng
    Physics Examination and Testing. 2025, 43(1): 1-5. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240016
    Abstract (58) Download PDF (1)   Knowledge map   Save
    The corrosion behavior of Q235B carbon steel for tank in acidic sulfolane solution at two typical temperatures, i.e., 30 ℃ and 50 ℃, was investigated and analyzed by static coupon method,electrochemical impedance spectroscopy and potentiodynamic polarization curve method. The results showed that the corrosion rate was fast at 50 ℃, which was nearly three times of that at 30 ℃. The electrochemical experiments indicated that Nyquist curve showed incomplete capacitive arc in the high-frequency region, and the radius of capacitive arc in the high-frequency region was small at 50 ℃. Due to the greater activation degree of sulfolane degradation at high temperature, the resistance of ions in the solution became smaller, leading to the aggravated corrosion, which was consistent with the result of static coupon method. With the extension of immersion time, the corrosion products of Q235B carbon steel during the immersion in acidic sulfolane solution had no protecting effect on the matrix. The self-corrosion potential shifted negatively, the polarization resistance decreased, and the corrosion resistance gradually decreased.
  • Failure analysis for breakage of rainwater grates
    LI Feng, LI Yi, WU Haikun, YANG Yang, CHEN Xiaohan
    Physics Examination and Testing. 2024, 42(6): 29-36. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230123
    Abstract (58) Download PDF (0)   Knowledge map   Save
    A rainwater grate in one residential area fractured during use. The intact rainwater grates and fractured ones collected from the site were analyzed and compared by metallographic examination, scanning electron microscopy, and mechanical property testing. By combining with finite element simulation analysis, it was found that the material of the fractured rainwater grate was gray cast iron, which had relatively poor mechanical properties. Additionally, due to the existence of old damage in the fractured rainwater grate, its strength could no longer meet the requirements for pedestrian stepping, posing a safety hazard, and leading to breakage accidents when stepped on by pedestrians.
  • Influence of crack source welding method on drop weight NDT temperature
    DING Yang, ZHANG Maolong, XIE Jinghua, ZONG Hai, HOU Dongdong, LI Sihao
    PHYSICS EXAMINATION AND TESTING. 2024, 42(4): 6-12. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230086
    Abstract (57) Download PDF (82)   Knowledge map   Save
    The influence of crack source weld bead welding methods on the drop weight NDT temperature was studied using the drop weight testing machine and optical microscope. Different heat dissipation methods, different magnitudes of welding current, different weld bead lengths, and different weld bead widths were selected and investigated. The results showed that the heat dissipation method and welding current had a significant influence on the drop weight NDT temperature, while the length and width of weld bead had no significant impact. Meanwhile, the melting depth, the area of heat affected zone, and the area of coarse grain zone were the essential reasons to affect the drop weight NDT temperature.
  • Microscopic characteristics and field improvement of scratch defects in rough rolling region
    LIU Xuewei
    Physics Examination and Testing. 2025, 43(1): 57-62. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240021
    Abstract (57) Download PDF (1)   Knowledge map   Save
    In order to find out the causes of fine line-like defects at the edges of 20MnB hot rolled fine-blanking steel and propose the effective improvement measures, the micro-cracks were formed by pre-crack and fatigue vibration based on the microstructure analysis of detects in hot rolled plate. The sample with micro-cracks was used for high-temperature oxidation simulation experiments. The oxidation and decarbonization laws of microstructure near the micro-cracks were investigated. The results showed that the depth of oxidation dots was strongly correlated with heating temperature, which was the main basis for judging the formation temperature of defects. The microscopic characteristics in high-temperature oxidation simulation experiments were compared with the defects in hot rolled plate. It was considered that the edge defects in the hot rolled plates occurred in the rough rolling region. The typical microscopic characteristic was that there was an oxidation dot zone with a depth of less than 5 μm near the crack, as well as the slight grain growth and decarbonization or not in metallographic structure. According to the above conclusion, the equipment in rough rolling region was checked up, and it was found that the vertical roller surface was rough and there were adhesive steels on it, which were the main reasons to cause fine line-like defects. The lubrication process and working period of the vertical roller were adjusted. The percentage of the rolled oil was increased from 3‰ to 5‰. Finally, the fine line defects at the edges were significantly reduced.
  • Discussion on phase transformation law of SPHC3 steel in CSP ferrite rolling
    YANG Yalong, HE Xiaoqin, ZHANG Yang, WANG Binbin, ZHAO Mengying
    Physics Examination and Testing. 2025, 43(2): 1-7. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240038
    Abstract (56)   Knowledge map   Save
    To optimize the rolling process parameters of ferrite, dilatometric analysis and metallographic method were combined in this study to construct dynamic continuous cooling transformation (CCT) curve of undercooled austenite for the intermediate billet of SPHC3 steel during the transition from austenite to ferrite. The phase transformation law of SPHC3 steel was further analyzed in continuous cooling process, and the phase transformation points were determined. The experimental results indicated that, under constant deformation conditions, the increase of cooling rate would reduce the initial temperature of ferrite transformation (Ar3) and the austenite-to-pearlite transformation temperature (Ar1), while the phase transformation temperature range was widened. Thermal simulation experiments with varying deformation temperatures, deformation amount, and strain rates were conducted, supplemented by lever method of dilatometric curves, to explore the effects of process parameters on dynamic transformation points during austenite-to-ferrite transition. The results demonstrated that, when other deformation conditions were fixed, both Ar3 and Ar1 lowered with the increasing of deformation temperature; both Ar3 and Ar1 increased with the increasing of deformation amount; both Ar3 and Ar1 lowered with the increasing of strain rates. In industrial production, the phase transformation temperatures could be increased by lowering deformation temperature, increasing deformation amount, reducing strain rate, and decreasing cooling rate, thereby ensuring that the finish rolling occurred within ferrite region.
  • Experimental design of XRD testing based on three-axis sample stage
    ZHENG Xiaoke, YANG Zhuofan, WU Junning, WEI Feifei
    Physics Examination and Testing. 2024, 42(5): 6-9. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230117
    Abstract (53) Download PDF (36)   Knowledge map   Save
    X-ray diffraction (XRD) is the most important and fundamental testing method for modern material analysis. However, there are many strict conditions for sample preparation and testing when the standard flat sample stage is used. For example, a certain amount of powder samples is required, and block sample should meet certain size requirements. To solve the problem of complex sample preparation process in flat sample stage, an XYZ program automatic 3-axis sample stage based on polycrystalline X-ray diffractometer was designed for experimental design of powder and bulk samples. The results showed that the testing could be normally performed when the amount of powder sample was little or the size of block sample was small. Moreover, the measurement data were accurate and the operation was simple. The three-axis sample stage effectively solved the problem of small sample amount for scientific research through the combination of laser positioning and manual positioning. It was sample friendly. The sample preparation time was greatly shortened, which provided convenience for more efficient open and sharing.
  • Analysis of influencing factors in phase transformation test of hot formed steel
    LEI Na, ZHOU Zhichao, YANG Yanlong, ZHAO Naisheng, QIU Yu, SHAN Xianfei
    PHYSICS EXAMINATION AND TESTING. 2024, 42(4): 13-17. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230088
    Abstract (53) Download PDF (40)   Knowledge map   Save
    In order to improve the accuracy of phase transformation test data for metal materials, the thermal expansion method was employed to analyze various influencing factors in phase change tests using one kind of hot formed steel as the example. The results showed that the factors such as heating speed and top rod material had a significant impact on the test results, while the surface treatment method, zero displacement, vacuum degree, parallelism at both ends of the sample, and distance between thermocouple wire welding points had a relatively low influence on the test results. The development of appropriate experimental techniques and rigorous operational processes could reduce errors of the experimental data to a certain extent and improve the accuracy of experimental results.
  • Analysis of linear trace defect on the outside surface of 20# steel pipe sleeve parts
    LÜ Fang, HUANG Kaihua, HAO Yongjin, YU Lei, LI Yuejie, MA Ding
    Physics Examination and Testing. 2025, 43(1): 51-56. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240014
    Abstract (53) Download PDF (0)   Knowledge map   Save
    In the machining process of sleeve parts by one machine manufacturing shop, it was found that the surface of several steel pipe sleeve parts had linear longitudinally stripe defects and the surface quality was unqualified. After scraping the unqualified sleeve parts, the defects were damaged for analysis. Through metallographic detection, scanning electron microscope(SEM) and energy dispersive spectroscopy(EDS) analysis, the causes of defects were finally found out. There were some small skin warping defects on the surface of the tube billet before drawing. These small defects were lengthened longitudinally along the deformation direction during the drawing process, and finally became the folding defects distributed longitudinally in the extension pipe.
  • Analysis of total focusing method for ultrasonic phased array defect inspection
    YANG Bo, WAN Ce, WANG Yongfeng, SHEN Haihong, XU Lei, ZHANG Jianwei
    Physics Examination and Testing. 2025, 43(2): 38-42. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240028
    Abstract (53)   Knowledge map   Save
    Total focusing method (TFM) of ultrasonic phased array is a non-destructive testing method which combines phased array probe and total focus imaging technology. As a new non-destructive testing technology, it has attracted much attention in recent years. Total focusing method of ultrasonic phased array is based on the full matrix data acquisition (FMC) technology to obtain the detection data for signal processing. Compared with conventional ultrasonic phased array detection, full focusing method has higher imaging resolution and more accurate defect location. In this paper, the principle, characteristics and function of total focusing method of ultrasonic phased array are described in detail, and the conventional phased array detection and full focusing detection technology are compared and analyzed by using standard test blocks, which has certain significance for further understanding and popularization of total focusing method of ultrasonic phased array.
  • Determination of F and Fe elements in the non-stick pan inner coating
    SHANG Junling, LIU Jinyang, CHEN Jian
    Physics Examination and Testing. 2024, 42(6): 15-19. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240001
    Abstract (51) Download PDF (0)   Knowledge map   Save
    The mapping of elements in the non-stick pan inner coating were analyzed using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) under acceleration voltage of 10 kV. The results showed that the overlapping between the K spectrum series of F element and L spectrum series of Fe occurred led to the difficulty to distinguish F and Fe elements in the mapping. By changing the spectrum series of Fe from L to K or employing the TruMap function of EDS software, the true distribution of Fe element could be obtained. By combining the point spectrum fitting with quantitative analysis results, the true position of F element in the mapping was determined.
  • Application of X-ray photoelectron spectroscopy in analysis of passivation film of tinplate
    WANG Yaqing, ZHANG Lixia, SHI Xuexing
    Physics Examination and Testing. 2024, 42(5): 22-26. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230112
    Abstract (51) Download PDF (36)   Knowledge map   Save
    The passivation film of tinplate was characterized by X-ray photoelectron spectroscopy. The testing parameters were varied to investigate the influence of different conditions on the elemental analysis of passivation film of tinplate. The results showed that the larger the test spot size, the higher the peak intensity and the narrower the half-peak width of spectral peak. The pass energy of the full spectrum test was improved, and the effect was the best when the pass energy in high-resolution narrow spectrum test was controlled at 20-50 eV. The thickness of polluted carbon and passivation film of tinplate was studied by the depth profiling technique of X-ray photoelectron spectroscopy. The results showed that the thickness of polluted carbon film on tin plate surface was about 2 nm, and the thickness of passivation film was about 28 nm. The measure result of passivation film thickness was basically consistent with that obtained by glow discharge spectrometry.
  • Test and analysis of plating leakage defects on surface of hot galvanized BH180 sheet
    LONG Xukai, ZENG Songsheng, YANG Zheng, ZHOU Yu, ZHOU Huanneng, LIU Xueliang
    Physics Examination and Testing. 2024, 42(5): 32-38. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230115
    Abstract (51) Download PDF (39)   Knowledge map   Save
    The issue of surface plating leakage on bake-hardened steel BH180 products produced by a hot-dip galvanizing production line in a domestic steel plant was analyzed and studied. The formation mechanism of plating leakage was analyzed by observing the macroscopic and microscopic morphology of defects as well as detecting the composition of defects. It was found that there were numerous pits on the surface of substrate where the defects appeared as orange peel shapes. Even after cleaning, the grease mixture residue remained in these pits. The organic residues were carbonized and deposited within the pits during annealing, which reduced the wettability of zinc solution and inhibited the formation of Fe2Al5 inhibition layer on the substrate surface. As a result, the plating leakage defects were generated. By comparing the composition of the defective coil substrate with that of the normal coil substrate, it was found that the boron content in the defective substrate exceeded the standard. The trace boron elements were segregated at the grain boundaries, which led to the existence of mixed structure of coarse block and long grain and fine grain in the substrate. The hot-rolled substrate with mixed grain structure would form orange peel pits after pickling and cold rolling. After strictly controlling the boron content in BH180 substrate and improving the process efficiency of galvanized cleaning section, the problem of plating leakage of BH180 could be effectively solved.
  • Discussion on software validity confirmation of tensile testing machine
    CAI Yu, XU Lei, LI Jun, YIN Xuqiang, WANG Linhui, ZHU Yin
    Physics Examination and Testing. 2025, 43(2): 58-62. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240029
    Abstract (51)   Knowledge map   Save
    With the development of computer processing technology, the application of software in testing and analysis has become common, and the relevant standards such as API Q1 and ISO/IEC 17025-2017 also put forward requirements for software confirmation. Therefore, how to evaluate the accuracy and reliability of test software is particularly important. In this study, the room temperature electronic stretcher was taken as an example, and the tensile software was confirmed according to the control points in appendix C of GB/T 228.1-2021. The automatic calculation of sampling frequency, yield strength, tensile strength and tensile rate of data acquisition and analysis software was verified. The verification principle, implementation method and steps were described in detail. After verification, the parameters automatically collected by the software could meet the requirements of standard, which indicated that the verification method was reliable.
  • Cause analysis of flaw detection disqualification of steel for DH36 offshore platform and process improvement
    LI Wei, NIAN Yi, LI Jiale, ZONG Youcheng, ZHANG Liqiang
    Physics Examination and Testing. 2024, 42(5): 44-49. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230121
    Abstract (50) Download PDF (41)   Knowledge map   Save
    Utilizing ultrasonic flaw detection technology, a comprehensive inspection was conducted on steel plates after rolling, and a systematic analysis was performed to identify the causes of flaw detection. The causes of cracks and inclusions result from Nb and Ti were elaborated, revealing the microstructures and maromorphology of these defects. Adopting KR hot metal desulfurization: The hot metal adopts a full slag removal process, with the incoming S less than 0.005%, hot metal temperature more than 1 340 ℃, converter compound blowing throughout the process with argon, endpoint carbon content controlled between 0.04%-0.06%, utilizing a slide gate for slag retention, and a steel tapping time more than 4 minutes, etc. The implementation of these measures is vital for ensuring the safety and reliability of steel used in ocean platforms and contributes to quality control in the steel industry.
  • Optimization of austenitic grain display method for 45 steel and 20CrMoH steel
    CHEN Chao
    Physics Examination and Testing. 2024, 42(5): 27-31. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230104
    Abstract (48) Download PDF (27)   Knowledge map   Save
    The austenite grain size display of 45 steel and 20CrMoH steel was optimized. The commonly used picrate corrosion method was selected for the detection of austenite grain size. The corrosion temperature and corrosion time were controlled to optimize the detection method of austenite grain size display for 45 steel and 20CrMoH steel, so that the austenite grain size display was clearer.
  • Influencing factors analysis on the detection stability of elongation after fracture for ultra-high strength steel
    CAI Hongmei, LI Ji, HOU Yongliang, YANG Yuqian, MIAO Zheng
    Physics Examination and Testing. 2025, 43(1): 10-13. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240019
    Abstract (45) Download PDF (0)   Knowledge map   Save
    By comparing specimen microstructure of the processed surfaces obtained by the three different sample preparation processes,i.e.,wire cutting,punching processing,and laser cutting, as well as the stability of elongation after fracture,the most suitable sample preparation process for ultra-high strength steel was screened out. According to standard requirements, the influences of three different transition arc radii on the detection stability of elongation after fracture for ultra-high strength steel were analyzed. Moreover, the influences of three different rate switching point parameter settings on the stability were also investigated. At the same time, the stabilities of measured elongation after fracture for ultra-high strength steel by laser extensometer and mechanical extensometer were compared. Based on the above research, the suggestions for detection of the elongation after fracture of ultra-high strength steel in the laboratory were put forward: laser cutting was recommended for sample preparation; the transition arc radius was selected as 35 mm; when the rate switching point parameter was set to 0.10 or 0.15, the data were most stable;if the elongation after fracture of ultra-high strength steel was automatically measured, the data obtained by laser extensometer were more stable than those obtained by mechanical extensometer.
  • Cause analysis of pinion shaft fracture
    ZHANG Demei, LIANG Xiaodong, WANG Shuangye
    Physics Examination and Testing. 2025, 43(1): 45-50. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240009
    Abstract (45) Download PDF (0)   Knowledge map   Save
    There was abnormal noise for one air conditioning system equipment during commissioning after installation, and it could not continue to run after about 400 h. The dismantling results showed that the threaded part of shaft end of compressor pinion shaft was broken. The pinion shaft was comprehensively analyzed through chemical composition, hardness, mechanical property, microstructure and micromorphology of fracture. The results showed that the carbon content in pinion shaft exceeded the upper limit specified in EN10084-2008. The hardness exceeded the technical requirements of the product. The percentage elongation after fracture and the percentage reduction of area were lower than technical requirements of the product. There was segregation of alloying elements. The cracks were generated at the root of thread in thermal refining. The combined effect of these factors caused the premature failure of pinion shaft.
  • Development of SCM440 hot rolled large coil for cold heading standard parts
    HU Juan, LEI Zhongyu, LIU Jinyuan
    PHYSICS EXAMINATION AND TESTING. 2024, 42(4): 1-5. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230079
    Abstract (44) Download PDF (68)   Knowledge map   Save
    The production technology, process control and quality of SCM440 hot rolled coil for high grade cold heading standard parts were introduced. In the steelmaking process, the converter smelting, LF+RH refining, and continuous casting processes should be strictly controlled to ensure the chemical composition and purity of steel. Water cooling was adopted in the rolling process to maintain the coiling temperature at 840-870 ℃. Meanwhile, the cooling speed of the rolled coil was controlled below 2 ℃/s through the adjustments in insulation cover opening/closing and fan air volume. According to the testing, the hot rolled structure of Ø26 mm SCM440 hot rolled large coil was bainite + perlite + ferrite with a grain fineness number of 9-10. Additionally, the ratio of total decarburization layer was ≤1%, and the pass rate for 1/2 cold forging was 100%. The results indicated that SCM440 large coil could fully meet the processing requirements of grade 12.9 cold heading steel.
  • Analysis and improvement measures of surface scratch defect of spring steel for railway spring bar
    ZHAO Yue, LU Jian, CHEN Kun, WU Qing
    PHYSICS EXAMINATION AND TESTING. 2024, 42(4): 48-52. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230076
    Abstract (44) Download PDF (45)   Knowledge map   Save
    In view of the scratch defects on the surface of spring steel for railway spring bar, the experimental detection and analysis were conducted, and the reasons were discussed to find out the root causes of scratch defects. The results showed that the long scratches were the sliding friction between the guide groove between the exit of the rolled part and the finished product frame to the 3# shear and the conveying roller frame after the 3# shear. A groove was formed after long-term friction. The intermittent scratches were produced by contact friction between rolled pieces and skirt and skirt rollers with sharp corners during high-speed discharge. Combining with the quality problems existing in the production process, the improvement measures were put forward to effectively control the scratch defects on the surface of the spring steel for the railway spring bar. The quality of final products was good, which was recognized by the customers.
  • Analysis on grinding crack of φ135 mm 48MnV steel crankshaft
    WANG Qiang, ZHAO Sixin, YU Dajiang, GAO Jiaqiang
    Physics Examination and Testing. 2024, 42(6): 23-28. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240010
    Abstract (44) Download PDF (0)   Knowledge map   Save
    During the grinding and inspection stage, some surface-initiated turtle-back cracks were observed on the connecting rod neck of φ135 mm 48MnV steel crankshaft after surface induction hardening and tempering. These surface cracks were analyzed by optical microscope, scanning electron microscopy equipped with an energy dispersive spectrometer, and microhardness tester. The results indicated that the observed cracks were grinding cracks. The cracks only existed on the surface layer of the hardened layer, with a depth of about 340-510 μm. The surface layer of the hardened layer had the lowest hardness. Then it firstly increased and then leveled off, and gradually decreased to the hardness of connecting rod journal substrate. The microstructure of the connecting rod journal from the hardened layer to the substrate was: quenched martensite + residual austenite → tempered martensite + tempered troostite → tempered martensite → ferrite + pearlite.
  • Analysis and improvement of scale-shaped skin defects in X80M pipeline steel
    LI Yuelin
    Physics Examination and Testing. 2024, 42(6): 37-41. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230125
    Abstract (43) Download PDF (1)   Knowledge map   Save
    The X80 grade pipeline steel products have been widely used in domestic oil and gas pipeline transportation engineering. The X80M hot-coiled produced by a steel factory had some defects such as edge warping, which led to the unqualified problem of batch flaw detection after pipe manufacturing. The typical defects were selected for macro and micro analysis and energy spectrum analysis, and according to the results of slab nickel nail test, it was found that the defects were mainly caused by the large temperature drop of hot-coiled edge in the rolling process. By adopting various measures, such as corner cutting and grinding of the slab, optimizing the hot rolling secondary model, reducing descaling passes in rough rolling, and modifying the vertical roll pass, the proportion of hot-coiled with scaly skin defects had decreased to less than 5%. The scaly skin defect was also reduced, and the improvement effect was remarkable.
  • Ultrasonic test technology of cast steel for large butterfly valves used in hydropower
    ZENG Ling
    PHYSICS EXAMINATION AND TESTING. 2024, 42(4): 42-47. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230095
    Abstract (41) Download PDF (48)   Knowledge map   Save
    The embedded flaws of butterfly valve steel castings were detected by ultrasonic testing technology. In the establishment of detection process, the appropriate single/double crystal longitudinal wave straight probe parameters were selected through comparative experiments by combining the unique acoustic characteristics of steel castings. Moreover, the key points of the detection process for single crystal and double crystal straight probes were elaborated separately. On the basis of testing experience, the waveform characteristics and mechanisms of four typical clustered internal defects commonly found in large butterfly valve steel castings were summarized. It was proven that the composite testing process using single/double crystal longitudinal wave straight probes as a practical non-destructive testing technology could ensure that the steel castings of butterfly valves entering the precision machining process meet the corresponding quality requirements.
  • Fracture cause analysis of compressor piston rod and bolt
    ZHONG Hui, ZHAO Rui, XIE Jinpeng, ZHONG Zhenqian
    Physics Examination and Testing. 2025, 43(2): 30-37. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230061
    Abstract (40)   Knowledge map   Save
    A exhaust gas recovery compressor fractured during service. The on-site investigation revealed that all twelve connecting bolts on the cylinder body of compressor had fractured. In addition, compressor piston rod was also fractured. In order to determine the failure cause and prevent such incidents from happening again, the analysis of piston rod and bolts on chemical composition, mechanical properties, metallographic structure, and fracture morphology was conducted through experiments. The fracture cause was identified. The results showed that the failure mode of compressor bolts was the fatigue cracking when the alternating loads exceeded the fatigue limit of material. The main cause of early-stage cracking of bolts was the existence of excessive full decarburization layer on the surface of thread. After the fastening bolt fractured, the compressor run in a state of instability, and the piston rod was abnormally stressed and overloaded, which belonged to the late damage.
  • Water-immersion ultrasonic detection technology for titanium alloy structural component by direct laser deposition
    LI Feng, LIU Zhiyi, WANG Juntao, NING Ning, ZHAN Shaozheng, LÜ Hongtao
    PHYSICS EXAMINATION AND TESTING. 2024, 42(4): 26-31. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230081
    Abstract (39) Download PDF (46)   Knowledge map   Save
    The water-immersion ultrasonic detection of titanium alloy structural component by direct laser deposition was conducted using water-immersion ultrasonic C-scan testing system. The corresponding testing procedures were also established. The results showed that the testing procedure had the characteristics of high sensitivity and high signal-to-noise ratio. The proposed testing procedure was applied to the ultrasonic detection of some titanium alloy products by direct laser deposition, and the results were compared with the radiographic testing and penetrant testing. The effectiveness of this testing procedure was verified.
  • Discussion on material analysis assisted by scanning acoustic microscope
    SHEN Haihong, YANG Bo, XIA Peng, XU Lei, ZHOU Xiangqi, ZHANG Yubin
    Physics Examination and Testing. 2025, 43(2): 24-29. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240025
    Abstract (39)   Knowledge map   Save
    The microscopic analysis of materials is mainly carried out by means of destruction, such as optical microscope (OM), scanning electron microscope (SEM). Meanwhile, these destruction methods can only analyze the situation of surface, and the situation in whole volume cannot be reflected. How to select and process the analysis surface will directly affect the analysis results. The application of ordinary ultrasonic testing has a long history, but it cannot meet the requirements of material microscopic analysis when it is applied in millimeter defect detection of materials and parts. Scanning acoustic microscope (SAM) is a kind of C-scanning equipment with high precision scanning institutions and special software. The working frequency is high frequency ultrasound which is 100-1 000 times of ordinary ultrasound. The resolution of X/Y axis is up to 0.1 μm, and the resolution of Z axis is up to 5 μm, which can realize the analysis of micrometer-level defect (or tissue structure). It has multiple scanning modes including A, B, C, D, X, G, P and 3D, which can realize three-dimensional defect positioning, size measurement and area proportion analysis. The abnormal internal structure of materials can be accurately reflected, which can be used as the preliminary positioning and screening method for material analysis, or directly used in material analysis.
  • Corrosion behavior of as-forged and SLMed TC4 alloys in 3.5wt.% NaCl solution
    SHAO Yanjing, QIN Yue, QIAO Yanxin
    PHYSICS EXAMINATION AND TESTING. 2024, 42(4): 18-25. https://doi.org/10.13228/j.boyuan.issn1001-0777.20240027
    Abstract (38) Download PDF (55)   Knowledge map   Save
    The electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curves (PDP), and localized electrochemical impedance spectroscopy (LEIS) were utilized to investigate the electrochemical behavior of as-forged and selective laser-melted (SLMed) TC4 alloys in 3.5wt.% NaCl solution. Additionally, Mott-Schottky test and X-ray photoelectron spectroscopy (XPS) were employed to analyze the properties of the passive films formed on the surface of the alloys. The results indicated that the as-forged TC4 alloy possessed an α+β dual-phase structure, whereas the SLMed TC4 alloy was mainly composed of acicular α' martensite. Compared to the SLMed TC4 alloy, the as-forged TC4 alloy exhibited a higher polarization resistance, a lower corrosion current density, and a thicker passive film. The passive films on both alloys were found to be n-type semiconductors, but the as-forged alloy had a lower carrier density. The content of TiO2 in passive film was also higher, indicating that the corrosion resistance property of the as-forged TC4 alloy was better than that of SLMed TC4 alloy.
  • New Groove Design and Forming Simulation of Uniform Severe Strain of Bar Rolling
    LI Xue-tong,CAO Lei,WANG Min-ting,DU Feng-shan
    Chinese Journal of Iron and Steel. 2013, 31(2): 21-25.
    Abstract (1894)   Knowledge map   Save
    Through the discussion of the traditional caliber and the analysis of simulation result, a new groove design method for bar rolling of uniform severe strain was proposed based on the principle of severe plastic deformation to manufacture ultra-fine grain(UFG),and flat-oval groove type with the characteristic of multidirectional severe deformation was developed. The warm rolling numerical model of bar was established and analyzed by nonlinear finite element method. The laws of plastic strain distribution in cross-section of bar were analyzed between the new caliber and traditional caliber. The simulated results indicated that the new flat-oval caliber can be better to introduce the plastic strain to the center of cross section and get uniform severe strain under the condition of qualified size. The largest strain was more than 5.0 at the center of cross section, which meets the severe deformation condition to produce ultra-fine grain.
  • Effect of Rolls Surface Roughness on the Hot-Dip Galvanized Coating
    CHEN Li-zhang,SHI Jun-feng,ZHANG Guo-tang
    Chinese Journal of Iron and Steel. 2011, 29(5): 56-59.
    Abstract (3059)   Knowledge map   Save
    The pock flaws on the surface of the hot-dip galvanized coating will not only affect its appearance, but also the employing properties of the hot-dip zinc-coated sheets and coils, the pock flaws were observed and analyzed by SEM and energy spectroscopy; meanwhile the surface roughness of the entry loop rolls and delivery loop rolls were measured. Results indicated that the pock flaws were caused by the excessive surface roughness of the rolls which injured the coating. And the zinc particle will cause the pock flaws. These defects could be decreased by polishing and cleaning the rolls surface.
  • Effect of microstructure on properties of roll surfacing
    LIU Lu, GUO Jian, ZHAO Guang, LI Bo, ZHAO Jianglin, HAN Peng
    PHYSICS EXAMINATION AND TESTING. 2023, 41(4): 1-4. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220054
    Abstract (144) Download PDF (1093)   Knowledge map   Save
    The service life of roll surfacing layer is closely related to the surface hardness and quality of surfacing alloy, while the surface hardness is closely related to the microstructure of the surfacing alloy. The surfacing alloy was prepared on 45 # steel substrate by the submerged arc surfacing technology using high-chromium molybdenum flux cored wire as the surfacing welding material. The alloy layer deposited by 420L welding wire had the dendritic structure composed of Fe-Cr solid solution and carbide, while the alloy layer deposited by YD255Mo-S welding wire was mainly composed of the mixture of black acicular martensite and residual austenite. The average microhardness HV0.2 of alloy layers deposited by two kinds of welding wires was 620 and 634.6, respectively. The maximum error was 11.9% and 9.1%, respectively. The overall average hardness value of alloy layer welded with YD255Mo-S wire was high with little fluctuation. The relationship between the microstructure characteristics of surfacing alloy formed under two grades of welding wire and the surface hardness of the alloy was studied.
  • Change of new edition of GB/T 228.1-2021 and its comparison with American standard
    LIU Manyu, HUO Shubin, YANG Zaixun, ZHANG Lei, HAO Zenglong, ZHU Houguo
    PHYSICS EXAMINATION AND TESTING. 2023, 41(2): 59-64. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220031
    Abstract (2239) Download PDF (1055)   Knowledge map   Save
    GB/T 228.1-2021 Metallic Materials-Tensile Testing-Part 1: Method of Test at Room Temperature was officially implemented on July 1st, 2022. The main changes between GB/T 228.1-2021 and GB/T 228.1-2010 were compared, and the main differences between GB/T 228.1-2021 and ASTM E8/E8M-21 were summarized. The technical differences of the above standards were compared and analyzed in terms of the scope, nouns and terms, symbols, samples, and size measurement, testing equipment and accuracy, testing requirements and performance measurement, result rounding off and uncertainty in measurement. The results showed that the technical contents of GB/T 228.1-2021 had changed greatly compared with GB/T 228.1-2010, for example, adding two different types of strain rate control modes and the method for measuring the elastic modulus of metal materials by uniaxial tensile test, changing the estimation method of displacement rate of deformation compensation beam of testing machine system, etc. Compared with the above national standards, there were great technical differences between GB/T 228.1-2021 and ASTM E8/E8M-21, so we should be familiar with the relevant provisions during the test. Through the comparison of above standards, it was helpful for standard users to have a deeper understanding and use of relevant standards in actual production, teaching and scientific research.
  • Cracking failure analysis of low-chromium ultrapure ferritic stainless steel for flange
    WANG Zhijun, QI Jiangtao
    PHYSICS EXAMINATION AND TESTING. 2023, 41(4): 49-52. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220076
    Abstract (113) Download PDF (814)   Knowledge map   Save
    Low-chromium ultrapure ferritic stainless steel is one of the main products of flange steel.Some irregular crack defects were observed in the end of the stamped flange during inspection. The cracks occurred at the end face or single face in the thickness direction. A sample with dimension of 20 mm×20 mm was sampled from the cracking part of flange, and the chemical composition was determined by X-ray fluorescence spectrometer. The section perpendicular to the rolling direction of the sample was polished and etched by FeCl3+HCl mixed acid solution. The microstructure and morphology were observed by optical microscope (OM), and the precipitated phases of sample were analyzed by scanning electron microscope (SEM). The analysis showed that the annealing time at high temperature was too long, resulting in the precipitation of a large number of hard and brittle granular intermetallic compounds (Fe2Ti and Fe3P) in the crystal and grain boundary of the low-chromium ultrapure ferritic stainless-steel matrix. These precipitated phases were irregularly distributed in the form of strips along the thickness direction. The precipitation of these intermetallic compounds, especially the cold brittleness effect of P element, caused the increase of local stress concentration, leading to local cracking during cold working of flanges.
  • Application of thermal simulation method in kinetics of second phase precipitation
    LIU Yanning, LI Ba, LI Nan, WANG Zhe
    PHYSICS EXAMINATION AND TESTING. 2023, 41(3): 40-45. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230015
    Abstract (248) Download PDF (752)   Knowledge map   Save
    Two kinds of thermal simulation methods, i.e., stress relaxation method and double-pass compression method, as well as their specific research methods and application examples in the study of the second phase precipitation kinetics curve in steel were systematically introduced. The stress relaxation method used the stress relaxation process of the material to obtain the kinetics curve of the second phase precipitation in the steel at different temperatures. The double-pass compression method was used to study the kinetics of second phase precipitation at different temperatures by double-pass compression of samples in steel. Through practical application, it was found that the stress relaxation method had the advantages of short time and less sample demand, while the double-pass compression method could calculate the starting and ending points of precipitation more accurately, and obtain more accurate data, which was suitable for high-precision research. The application of two methods had achieved good results, which provided a reliable experimental method for the study of the second phase precipitation kinetics curve in steel. Moreover, they provided an important reference for the R&D and engineering design in metallurgical process of steel.
  • Analysis of corrosion resistance of 445J2 ferrite stainless steel
    REN Juanhong, CHEN Anzhong, GAO Renqiang, PAN Jixiang
    PHYSICS EXAMINATION AND TESTING. 2023, 41(2): 11-15. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220039
    Abstract (390) Download PDF (713)   Knowledge map   Save
    The microstructure and corrosion resistance of ultra-pure ferritic stainless steel 445J2 and austenitic stainless steel 316L were studied by means of microstructure analysis, tensile test, salt spray corrosion test, electrochemical test, and stress corrosion test. The results showed that 445J2 stainless steel had low work hardening orientation and good deep drawing formability. Compared with 316L, the 445J2 stainless steel had lower density, better thermal conductivity, smaller coefficient of thermal expansion, less thermal deformation, better salt spray corrosion resistance and pitting corrosion resistance. Moreover, it had no intergranular corrosion sensitivity and stress corrosion tendency. The 445J2 stainless steel could replace 316L austenitic stainless steel for the application in water system, building roof, curtain wall and many other fields with high corrosion resistance requirements.
  • Effect of indentation spacing on measured value of Vickers hardness
    ZHOU Siyu, CAI Jing, ZHANG Zhongyuan, ZHANG Hongyang, WANG Jian, ZHANG Jian
    PHYSICS EXAMINATION AND TESTING. 2023, 41(2): 26-31. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220028
    Abstract (195) Download PDF (705)   Knowledge map   Save
    Vickers hardness test is the most accurate test method in static hardness test. However, in the actual operation of Vickers hardness test, it will be interfered by many factors, thus affecting the experimental results. Several groups of parallel tests for Vickers hardness test on multiple standard plates were conducted using automatic Vickers hardness test equipment. The influence of indentation spacing on the measurement results was analyzed. The uncertainty of tested results was calculated according to GB/T 4340.1-2009. It was found that the larger the indentation spacing was, the smaller the uncertainty was, and more accurate the test result was. Some testing materials were selected to verify the above conclusions. At present, there was a lack of research on the influence of indentation spacing on hardness value.
  • Cause analysis of fracture of stop valve
    ZHANG Demei
    PHYSICS EXAMINATION AND TESTING. 2023, 41(4): 36-39. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220069
    Abstract (266) Download PDF (702)   Knowledge map   Save
    The fracture of stop valves was observed in batches after use for one year. The fractured stop valves were comprehensively analyzed by means of chemical composition, hardness, microstructure and fracture appearance. The results showed that the chemical composition of the stop valves could meet the requirements of national standards (the mass fraction of Zn exceeds 38% of the total mass fraction). There was no abnormality for the hardness and microstructure. The fracture appearance indicated that the stress corrosion was the main reason to cause the failure of stop valves. The combined effect of three factors, i.e., no stress relief annealing was conducted for this batch of stop valves, the tightening force was larger, and the environment humidity was high, caused stress corrosion of stop valves which had strong tendency to stress corrosion. As a result, the early fracture occurred.
  • Production practice of inclusion control in 9Ni steel for LNG storage tank
    HAN Qibiao, GAO Longyong, CHE Jinfeng
    PHYSICS EXAMINATION AND TESTING. 2023, 41(4): 27-30. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220056
    Abstract (132) Download PDF (691)   Knowledge map   Save
    During the production of 9Ni steel medium-thick plates 06Ni9DR, many batches were unqualified in ultrasonic flaw detection. The defective parts of the samples were inspected and analyzed using the metallographic microscope and scanning electron microscope. The results showed that there were a large number of CaO-Al2O3 inclusions (in length of 61-167 μm) accompanied by a small amount of MgO and sulfide in the steel, which was main reason for the unqualified flaw detection. Due to insufficient addition of aluminum in LF deoxidation, the burning loss of aluminum during refining led to further reduction of aluminum content. Aluminum was added in the later stage of LF treatment or in the process of RH treatment, thus a large number of such inclusions were generated. After taking some measures such as controlling the end-point carbon and oxygen content of the converter, extending the RH vacuum treatment time and soft blowing time, and ensuring sufficient liquid steel sedation time, the quantity of inclusions in the steel plate had been significantly reduced. Meanwhile, the proportion of unqualified ultrasonic flaw detection decreased from 8.11% to 0.2%.
  • Development of 55SiCr spring steel wire rod for high strength oil quenched and tempered steel wire
    SUN Xiaoming, GUO Xiaoxia, LI Shaojie
    PHYSICS EXAMINATION AND TESTING. 2023, 41(2): 1-4. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220026
    Abstract (318) Download PDF (688)   Knowledge map   Save
    The production process of 55SiCr spring steel wire rod for oil quenched and tempered steel wire was introduced. The hot-rolled spring steel coils for high-strength oil quenched and tempered steel wires were successfully trial-produced through the reasonable composition design and control, the use of low alkalinity refining slag smelting process, the optimization of high-wire heating process system and the appropriate controlled rolling and controlled cooling process. The results showed that the chemical composition, non-metallic inclusions, metallographic structure, grain size, decarburization layer and mechanical properties of 55SiCr steel for oil quenched and tempered steel wire could meet the customer's requirements. The tensile strength of steel wire rod after oil quenched and tempered could achieve 2 000 MPa grade, and the section shrinkage rate was higher than 40%. The oil quenched and tempered steel wire was cold rolled to produce the automobile suspension springs, and the fatigue life of springs could meet the customer's requirements.
  • Discussion on quantitative determination of different types of inclusions in rare earth weathering steel
    XU Jie, LI Lingxia, LI Jikang, CHEN Ying
    PHYSICS EXAMINATION AND TESTING. 2023, 41(3): 57-60. https://doi.org/10.13228/j.boyuan.issn1001-0777.20230002
    Abstract (159) Download PDF (673)   Knowledge map   Save
    In order to investigate the distribution situation of rare earth elements in steel, the contents of rare earth sulfide inclusions and sulfur-oxygen complex inclusions in rare earth weathering steel were accurately determined. Two kinds of weathering steels, i.e., Q235RE and Q335RE, were studied. The inclusions in steels were extracted by non-aqueous electrolytic process. Moreover, the types of inclusions, the separation methods and the contents of rare earths were investigated by X-ray diffractometer (XRD) and inductively coupled plasma emission spectrometer (ICP). The results showed that the inclusions in Q235RE and Q335RE were mainly manganese sulfide (Ce2S3) and sulfur-oxygen complex inclusions (RE)2O2S. Three separation methods, i.e., 1%-2% hydrochloric acid, 1%-2% nitric acid and 2%-3% EDTA, were used for the separation of inclusions in rare earth weathering resistant steel Q235RE. Only when EDTA was used for separation, the cementite and unstable rare earth sulfide inclusions could be dissolved, while the sulfur-oxygen complex inclusions were retained. Therefore, EDTA separation technology could be used to accurately determine the contents of rare earth elements in rare earth sulfide and rare earth sulfur oxide inclusions.
  • Drop hammer tear test and pendulum impact test of pipeline steel
    SHAN Xianfei, LEI Na, ZHAO Naisheng, YANG Yanlong, ZHANG Longhui
    PHYSICS EXAMINATION AND TESTING. 2023, 41(4): 11-14. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220068
    Abstract (184) Download PDF (669)   Knowledge map   Save
    The performance of drop hammer tear test and pendulum impact test of pipeline steel are two important parameters of materials, which can help determine the safety and reliability of materials or products. Two pipeline steel samples with different specifications and different properties were used to perform drop hammer tear test and Shaabi pendulum impact test at different temperatures. The impact shear section rate and the drop hammer shear area fraction in two test methods were compared. The difference and relationship were studied based on the test results. The results showed that the change laws of impact shear section rate and the drop hammer shear area fraction were basically consistent during the temperature variation for two pipeline steel samples with different specifications and different properties in drop hammer tear test and pendulum impact test.
  • Cracking analysis of stainless-steel tube in vertical heat exchanger
    XIONG Libin, MENG Ruoyu, OU Bingxian
    PHYSICS EXAMINATION AND TESTING. 2023, 41(2): 38-42. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220029
    Abstract (171) Download PDF (667)   Knowledge map   Save
    The causes for circumferential cracking of stainless-steel heat exchange tube in the vertical heat exchanger were analyzed by the means of macroscopic observation of crack morphology and corrosion morphology of adjacent carbon steel tube, physical and chemical analysis of material, metallographic examination, fracture observation by SEM and X-ray energy dispersive spectrometer, corrosive anion analysis of cooling water, etc. The results showed that the crack originated from the outer wall of the heat exchange tube. The crack morphology and fracture morphology showed the characteristics of stress corrosion, while the cooling water outside the pipe had high concentration of chloride ion and sulfate. Moreover, the local oxygen content in cracking area was relatively high. The analysis indicated that the stress corrosion was the cause for cracking of the heat exchange tube.
  • Characteristics of Phase Transformation in 4Cr16Mo Steel and 4Cr16MoN Steel
    YUAN Sen1,WU Xiaochun1,ZHUANG Yujian1,ZHANG Hongkui2,LUO Yi1
    Chinese Journal of Iron and Steel. 2011, 29(3): 1-4.
    Abstract (2878)   Knowledge map   Save
    The largescale production and heat treatment of 4Cr16MoN steel are provided by the equilibrium phase diagram and CCT curve of steel. The equilibrium phase diagram of 4Cr16MoN and 4Cr16Mo steel are calculated By JMatpro simulation software. Then the CCT curves are measured by DIL805A phase change thermal expansion. Here are the test conditions:1 050 ℃/s austenite, holding 5 min,cooling based on 10、3、12、1、05、01、008、005、003 ℃/s. The results showed that: in calculated equilibrium phase diagram of the two test steels, over a wide high temperature range the steel was maintained to be singlephase austenite, not δ ferrite; Two experimental CCT curves of the steels have independent pearlite and bainite regions; The critical cooling rate of P and B of 4Cr16MoN steel is 01 ℃/s and 12 ℃/s respectively, while the critical cooling rate of P and B of 4Cr16Mo steel is less than 003 ℃/s and 3 ℃/s.
  • Uncertainty analysis of measuring elastic modulus by static method and resonance method
    YU Jianxin, CUI Xiping, WANG Xiaopeng
    PHYSICS EXAMINATION AND TESTING. 2023, 41(4): 53-59. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220063
    Abstract (115) Download PDF (649)   Knowledge map   Save
    The elastic modulus of metal materials was measured by the static method and the resonance method, respectively. In the static method, an electronic universal testing machine and extensometer were used for the tensile test of dumbbell-shaped bar samples, and the slope of the elastic section of the engineering stress-engineering strain curve was used to calculate the elastic modulus. In the resonance method, the bending resonance test of rectangular free beam sample was carried out by using dynamic elastic modulus and damping analyzer, and the elastic modulus was indirectly measured according to the relationship between the elastic modulus and the fundamental bending frequency. According to the standard for evaluation and expression of uncertainty in measurement, the measurement uncertainty of elastic modulus by static method and resonance method was compared using 7075 aviation aluminum alloy as an example. The results showed that the maximum uncertainty of static method was the deformation error measured by extensometer, and the maximum uncertainty of resonance method was the thickness measurement error. The measurement results by resonance method were better than those by static method. The measurement uncertainty analysis could provide reference for the selection of measurement methods and evaluation of results of elastic modulus.
  • Heat Treatment to Improve the Fracture Resistance of the TiC Ceramic Cutter
    Chinese Journal of Iron and Steel. 2011, 29(1): 1-1.
    Abstract (3621)   Knowledge map   Save
    The heat treatment process of improving the toughness was brought forward by studying the effect of heat treatment on the microstructure of the 3Cr13 which is the matrix of the metal based TiC ceramic cutter. This heat treatment process could eliminate the brittle carbides distributed along the prior grain boundaries like a net and bring in refined martensite. Hence, the heat treatment greatly improved the toughness of the cutter’s matrix and effectively enhanced the fracture resistance of the cutter, resulting in a lower cutter fracture ratio.
  • Thermal Simulation Testing Machine Compression Test Analysis of the Temperature Jumping
    LI Hong-bin1,2,GE Xiao-hong3,MA Tao4
    Chinese Journal of Iron and Steel. 2011, 29(6): 9-11.
    Abstract (2835)   Knowledge map   Save
    In the process of Gleeble3500 cylinder one-way compression, the increasing of temperature at the moment of compression was caused by multiple reasons. By means of different test cases of compressing the cylinder with Gleeble3500, the effects of larger space between the thermocouples and the decreasing of the workpiece resistance on the temperature detection were analyzed.
  • EBSD sample preparation and characterization method of oxide scale on the surface of hot-rolled steel strip
    ZHANG Qi, MI Zhenli, ZHU Rong, WANG Mai, WU Yanxin, LI Lei
    PHYSICS EXAMINATION AND TESTING. 2023, 41(1): 21-24. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220010
    Abstract (208) Download PDF (615)   Knowledge map   Save
    In order to obtain an EBSD sample preparation method suitable for oxide scale on the surface of hot-rolled steel strips, the oxide scale generated on the surface of 22MnB5 hot-rolled sheet was selected as the research object. The surface EBSD scanning effects of hot-rolled sheet strip under three sample fixture methods (i.e., cold mounting, hot mounting and clamp clamping) and two sample preparation methods (i.e., vibration polishing and manual sample preparation) were compared. The results showed that the hot mounting method was the most suitable fixing method for polishing the surface of hot-rolled strip steel with oxide scale. Both vibration polishing and manual sample preparation methods could characterize the microstructures (such as morphology, phase composition and grain size) of oxide scale on the surface of hot-rolled steel strip. The manual sample preparation method proposed could shorten the sample preparation time and cost while ensuring the sample preparation effect.
  • Cause analysis of abnormal etching test of 18CrNiMo7-6 wind power planet wheel forgings
    DONG Juan, CAI Fengwei, CHEN Yongxiang
    PHYSICS EXAMINATION AND TESTING. 2023, 41(4): 40-44. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220070
    Abstract (129) Download PDF (597)   Knowledge map   Save
    The chemical composition, gas content, hardness and non-metallic inclusions of 18CrNiMo7-6 wind power planet wheel forgings were tested to find out the reasons for the abnormal etching test. The results showed that 18CrNiMo7-6 molten steel was not completely deoxidized or it contacted with the air due to the imperfect protective measures during pouring. Al in the steel was oxidized to Al2O3, which was eventually remained and dispersed in the wind power planet wheel forgings, resulting in unqualified forgings etching detection. The forging samples were reanalyzed by etching test. The macroscopic examination on any cross section showed that the same black etching points could be found, which verified the analysis conclusion.
  • Design of Eccentric Tension Mechanism Used on Universal Material Testing Machine
    ZHANG Niansheng,ZHU Dequan,XU Wei,ZHANG Xiaolong, JIN Dingzhou,ZHAO Hong
    Chinese Journal of Iron and Steel. 2011, 29(3): 16-18.
    Abstract (3281)   Knowledge map   Save
    Experiment of eccentric tension is one of teaching content of material mechanics experiment. The experiment of eccentric tension can not be conducted directly on the universal material testing machine. One simple eccentric tension mechanism, which is fixed on the universal material testing machine, can test the strain of deformation under load of tension and bending so as to compute the maximum stress of material. And the function of universal material testing machine is expanded as well.
  • Analysis on influence of defect length on magnetic flux leakage test results of round rod
    HU Baishang
    PHYSICS EXAMINATION AND TESTING. 2023, 41(3): 11-15. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220051
    Abstract (156) Download PDF (583)   Knowledge map   Save
    The relationship between the reliable detection length of artificial groove damage on the surface of round rod and the width of magnetic flux leakage detection channel was analyzed. Moreover, the detection and determination of the defect signal under the condition of defect signal length suppression was also investigated. The formation of the detection signal caused by the depth variation of the natural defect and the application conditions of the length suppression of the defect signal were analyzed. The "uncertainty principle" of magnetic flux leakage detection of round rod was obtained, and the detection of natural defects on round rod was a probability event. Finally, the empirical measures to improve the reliability of magnetic flux leakage for surface defects of round rods were proposed.
  • Production practice of hardness control for high wear resistant round steel
    LI Jinhao, WANG Zongbin
    PHYSICS EXAMINATION AND TESTING. 2023, 41(3): 1-6. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220034
    Abstract (185) Download PDF (574)   Knowledge map   Save
    It was found that the hardness exceeded the standard when producing ø110 mm high wear-resistant alloy steel in the new medium-sized workshop of Special Steel Group. The CCT curve of the steel was measured through the thermal simulation test. The influence law of different cooling rate on phase transformation and microstructure hardness was obtained. The results showed that when the cooling rate was not higher than 0.2 ℃/s, the ferrite and pearlite transformation mainly occurred, and the hardness was not higher than 20.5HRC. When the cooling rate was in range of 0.5-2 ℃/s, the bainite and martensite transformation mainly occurred, and the hardness was in range of 40-51.7HRC. When the cooling rate was not less than 4 ℃/s, the martensitic transformation mainly occurred, and the hardness was less than or equal to 54.4HRC. According to the CCT curve, the round steel with hardness less than or equal to 21HRC could be obtained only when the cooling rate was controlled below 0.2 ℃/s in the rolling process in the workshop.
  • Effect and Analysis on the Experiment of HotCold Fatigue Test Controlled Temperature
    ZHANG Shanye,GAO Yifei
    Chinese Journal of Iron and Steel. 2011, 29(3): 5-7.
    Abstract (2798)   Knowledge map   Save
    Hotcold fatigue performances of the same kind of steel at different temperatures in different ways were studied. One way is via controlling the test temperature strictly, and another is through test standard. The results showed that all the cracks were initiated from the notch. The fatigue crack based on the experimental is larger. When the controlled temperature is closer to the room temperature, the two sets of test data are closer as well.
  • Effect of Heat Treatment on the Microstructure and Mechanical Properties of Austenite Stainless Steel 022Cr17Ni12Mo2
    LI Jianchun,ZHANG Zhiwei,ZHANG Shoulu
    Chinese Journal of Iron and Steel. 2011, 29(3): 8-11.
    Abstract (2916)   Knowledge map   Save
    Effect on the microstructure and mechanical properties of austenite stainless steel 022Cr17Ni12Mo2 of different heat treatment processes were investigated. Results show that as the heating temperature is increased from 950 ℃ to 1 250 ℃, the grain size becomes coarse, the α phase content drops at first then rises and arrives the lowest point at 1 150 ℃; the strength Rm、Rp02 and Rp10 decrease a little at different extents and the plasticity improves evidently. The cool manners have little impact on the grain size、strength Rm and elongation ratio, while comparing to air cooling，water cooling would be propitious to reduce the content of α phase, furthermore the strength Rp02 and Rp10 increase by 30-40 MPa.
  • Discussion on influencing factors of harmful intermetallic phase measurement in welding material 2209
    LIU Manyu, GUO Xiao, WANG Qingjiang, HU Xiaobo, MA Jianzhao, ZHANG Biying
    PHYSICS EXAMINATION AND TESTING. 2023, 41(3): 33-39. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220072
    Abstract (162) Download PDF (566)   Knowledge map   Save
    The method C in ASTM A923-2014 for the detection of harmful intermetallic phases in dual phase steel (Standard Test Methods for Detecting Detrimental Intermetallic Phase in Duplex Austenitic/Ferritic Stainless Steels) does not clearly specify the sampling location and size of welding materials. Through the discussion of sampling method, sample preparation method, composition gradient rule at different positions from the fusion line and measurement factors affected by different weld bead heat, the influence of the above factors on harmful intermetallic phases of deposited metal in 2209 automatic TIG welding was investigated by optical microscope (OM), spark discharge atomic emission spectrometry and energy disperse spectroscopy (EDS). The results showed that the nitrogen element value and ferrite content were the important factors influencing the harmful intermetallic phase. After wet grinding using abrasive paper (>6.5 μm) and alcohol. The sampling in a single pass and more than 7 mm away from the fusion line could fairly and objectively evaluate the harmful intermetallic phase in dual-phase steel 2209.
  • Relationship between strain hardening index (n) of metal sheet and its yield ratio
    WANG Feilong, QIN Rongguang, ZHOU Sanbao, YIN Jingjing, JIN Yang
    PHYSICS EXAMINATION AND TESTING. 2023, 41(1): 16-20. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220005
    Abstract (279) Download PDF (563)   Knowledge map   Save
    Based on the Hollomon relation, the corresponding relationship between the n value and the yield ratio was deduced. According to this formula, the value of n of one material with certain thickness was firstly measured, which was then substituted to obtain the value of material constant C. For the materials of this type of steel with other thicknesses, the measurement of yield strength Rp0.2 and tensile strength Rm was only required to calculate the value of n according to the formula. The calculation values and measurement values of n of typical material were compared. The results showed that the proposed method for the calculation of n was accurate and simple to use, which greatly simplified the work of determining the n value of the same steel type. This method was especially applicable for the estimation of n value of ultra-thin materials or ultra-thick materials, which was difficulty measured in the laboratory.
  • Test and analysis of needle-like metallographic sample in micro-nano scale
    YANG Xiao, PAN Hengpei, WANG Shining, LI Xuefeng, ZHANG Xinyao, GAO Lingqing
    PHYSICS EXAMINATION AND TESTING. 2023, 41(4): 20-23. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220061
    Abstract (116) Download PDF (562)   Knowledge map   Save
    In the process of metallographic analysis, the insetting of needle-like sample in micro-nano scale will easily cause the capillary phenomenon, which leads to the limited resolution of metallographic structure. As a result, it is difficult to accurately evaluate the micro structure. The needle-like sample in micro-nano scale were treated by grinding and polishing, and then eroded with the chemical reagents. After that, the sample was placed in ethanol and acetone solution for ultrasonic treatment followed by drying with a hair dryer. The results showed that due to the low melting point and high volatility of acetone solution, the addition of ultrasonic treatment in acetone solution in the process of conventional micro-nano metallographic sample could effectively remove the residual solution between the mosaic material and the sample. The occurrence of capillary phenomenon was reduced, which could ensure the clear observation of metallographic sample as well as the effective characterization of microstructure.
  • Cause analysis of tube head leakage of air cooler
    GUO Haixia, WANG Shining, CAI Haichen, ZHANG Jiaqi
    PHYSICS EXAMINATION AND TESTING. 2023, 41(1): 46-50. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220018
    Abstract (180) Download PDF (543)   Knowledge map   Save
    The leakage of pipe head (at the weld of tube sheet welded joint) occurred in the vulcanization process of diesel hydrotreating air cooler during running. The failure mode and reason were found through the microscopical examination, composition and microstructure analysis, and corrosion characteristic analysis of the pipe head of air cooler. It was found that the failure mode was sulfide stress corrosion. There were two reasons. One reason is the improper control of welding process. The welding cooling speed was fast, resulting in the formation of hardened structure. Another reason is the post weld heat treatment (PWHT) was also insufficient and the hardened structure was not improved.
  • Fracture cause analysis of ductile iron planet carrier
    LIU Yan, LI Xuefeng, GUO Haixia, YUAN Xiaodong, WANG Shining
    PHYSICS EXAMINATION AND TESTING. 2023, 41(1): 35-39. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220013
    Abstract (167) Download PDF (540)   Knowledge map   Save
    The ductile iron planet carrier fractured in the process of use, the location of the fracture is between two planet holes. Through the comprehensive analysis of the planet carrier by means of macro analysis, micro analysis, mechanical properties and other analysis, it is determined that the fracture mode of the planet carrier is fatigue fracture, the fatigue expansion is sufficient, no phenomenon of excessive local force was found, and there are shrinkage porosity defects at the cracking position. The existence of shrinkage defects cut off the internal continuity of the material, resulting in the reduction of the strength of the fracture site, make the parts crack before reaching the fatigue strength of the material, especially the parts subjected to periodic alternating load. The shrinkage is serious and produce prematurely extending to the surface of the parts, so that the stress concentration coefficient at the defect on the surface of the part increases sharply, fatigue cracks resulting in early fatigue failure of parts.
  • Calculation of Phase Equilibrium Temperature of Ae3 and Ae1 for TRIP Steel
    WANG Ping1,MENG Lingyou2，YOU Kai1
    Chinese Journal of Iron and Steel. 2011, 29(3): 12-15.
    Abstract (3897)   Knowledge map   Save
    By using of the super element model in association with the LFG model, the equilibrium concentration of xγ/αC, driving force for proeutectioid ferrite and pearlite transformation, ΔGγ→α+γ1 and ΔGγ→α+cem, and thermodynamic equilibrium temperature of Ae3 and Ae1 were calculated for TRIP steel, in addition, the influence on TRIP steel of different chemical composition and hot deformation conditions was discussed. The predicted and measured Ae3 and Ae1 for undeformed TRIP steel have good agreement, which shows that the calculations on phase equilibrium temperature in the paper is sufficiently accurate and reliable.
  • Method and device for continuous processing of tensile specimen of plate with different specifications
    HUANG Chengjie
    PHYSICS EXAMINATION AND TESTING. 2023, 41(1): 1-7. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220008
    Abstract (169) Download PDF (526)   Knowledge map   Save
    A special four-position clamp was designed to replace the single-position clamp. The whole-process numerical control macro program and directional precision compensation numerical control macro program were developed for continuous processing of tensile specimen of plate with different specifications. A new processing method and flow were formed. Through practical application, it could effectively save the non-maneuvering time of machine tool in machining process and maximize the efficiency, which solved the problems of precision error caused by tool wear and material cutting performance, and the deviation of the axis between the two heads of sample and the parallel part. The operation in the proposed method was simple and the continuous machining process was stable. This method had important practical significance in reducing labor intensity, shortening process, reducing tool consumption and realizing unattended machining.
  • Effect of surface contamination on properties of FGH4097 part after stable heat treatment
    ZHANG Anqin, ZHANG Linjia, XU Yongtao, WANG Jiang
    PHYSICS EXAMINATION AND TESTING. 2023, 41(1): 8-11. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220015
    Abstract (167) Download PDF (526)   Knowledge map   Save
    The influence of surface pollution and discoloration after stable heat treatment on the properties of high temperature alloy products prepared from FGH4097 powders was studied. The results showed that the surface contamination discoloration of FGH4097 powder superalloy parts after stable heat treatment was due to the surface oxidation of the parts. The discoloration layer was a thin oxide film. The performance test indicated that the surface pollution and discoloration had little influence on the performance of parts, which could meet the use requirements.
  • Automatic water flow regulation system for rotary ultrasonic testing
    WANG Xiaowen, ZHANG Guangxin, ZHANG Zhenhua
    PHYSICS EXAMINATION AND TESTING. 2023, 41(3): 7-10. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220046
    Abstract (168) Download PDF (525)   Knowledge map   Save
    The probe rotary ultrasonic testing can achieve rapid and automatic detection, and has been widely used by various steel mills. During flaw detection, a water ring is filled between the probe and the workpiece for inspection, and water serves as the coupling medium. It is necessary to solve the problem of rapid stability. The water flow and bubbles can affect the emission and reception signals of ultrasonic waves, leading to a decrease in detection sensitivity, and resulting in defect misdetection and missed detection. In order to improve this phenomenon, an automatic water flow regulation system was designed, which consisted of a programmable logic controller (PLC), an actuator, a flow regulation device, and a flow measurement device. In order to meet the precise regulation of water flow, the system adopted closed-loop control. The control quantity was obtained by inputting the given flow setting value and the deviation value after flow measurement through proportional, integral, and differential (PID) algorithm calculation. It acted on the water flow adjustment device and automatically adjusted the valve opening size, thereby achieving continuous and stable operation of the water supply system, which improved the detection efficiency of the flaw detection equipment and reduced the labor intensity.
  • Cracking analysis of 42CrMoA roller shaft end
    LIU Guijiang, TENG Zhengde, SHAN Mingyan, YANG Yongfeng, LU Wei, WANG Junmin
    PHYSICS EXAMINATION AND TESTING. 2023, 41(4): 24-26. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220055
    Abstract (110) Download PDF (518)   Knowledge map   Save
    The macroscopic examination, chemical composition and micro failure analysis were conducted for the cracking defect of the end of 42CrMoA roller shaft. The failure analysis showed that the cracking source of the roller shaft was the original end crack of the raw material. The process investigation and discussion analysis confirmed that the original end crack of raw materials was the sawing crack formed in the cold cutting process of grinding wheel saw. The main cause of sawing cracks was the combined effect of steel cooling stress and sawing thermal stress. The occurrence of sawing cracks could be prevented by annealing the steel and cooling slowly in pits.
  • Test method of austenite grain size of SiCr spring steel heat-treated wire
    JIN Tao, SUN Fengyuan, WANG Haihua, ZHANG Jianfeng, ZHENG Xiaowei
    PHYSICS EXAMINATION AND TESTING. 2023, 41(4): 15-19. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220052
    Abstract (226) Download PDF (516)   Knowledge map   Save
    SiCr spring steel heat-treated wire was used as the sample. The austenite grain size was tested by direct hardening method and oxidation method. In the direct hardening method for the test of austenite grain size of SiCr spring steel heat-treated wire, the sample was etched with 4% nitric acid alcohol solution. The results showed that the appearance of martensite could not be restrained, leading to the unclear austenite grain boundary when observed under a microscope. As a result, the grade of austenite grain size could not be accurately determined. For the oxidation method, the austenite grain boundary of spring steel heat-treated wire was clear under the microscope. The heating temperature was adjusted by measuring the phase transition temperature and phase transition kinetic curve. The holding time of temperature was determined according to the sample size. The optimal heat treatment process for SiCr spring steel was heating at 810 ℃ for 30 min, and it could be close to the austenitic grain size in real spring steel heat-treated wire. This study could guide the technological breakthrough of heat treatment in spring wire drawing plant to improve the performance of spring steel wire.
  • Application of laser confocal microscope in surface morphology characterization of DC04
    YANG Weiyu, LIU Yan, ZHANG Xiaolei, WANG Yanan
    PHYSICS EXAMINATION AND TESTING. 2023, 41(2): 21-25. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220025
    Abstract (209) Download PDF (515)   Knowledge map   Save
    The surface micromorphology of cold rolled automobile steel has an important influence on its properties such as stamping, coating, oil storage and corrosion resistance. The surface morphologies of DC04 produced by three different steel plants were characterized by OLS5100 laser confocal microscope, which were also compared with the images collected by scanning electron microscope. Meanwhile, the non-uniformity, height distribution and finish of surface micromorphology were evaluated by parameter characterization of laser confocal microscope. The test results showed that the surface topography images collected by laser confocal microscope had clear three-dimensional appearance and strong stereoscopic sense. The surface pits of DC04 produced by plant A were large and unevenly distributed, and the rolling marks at the bulge were significant. The surface pits of DC04 produced by plant B and C were many, and the surface micro-geometric morphology had a higher degree of regularization. The surface of the bulge was smooth, and the transition with the pit was smooth. The order of surface micromorphology non-uniformity of DC04 in the three steel plants was plant A > plant B > plant C, while the order of height distribution and finish was plant A < plant B < plant C.
  • Cause analysis of flaw detection unqualified of 4130X continuous casting open cast furnace steel pipe
    ZHANG Xinwen, SHI Jiakai, ZHANG Chunxiang, CHEN Kai, XUAN Kangle
    PHYSICS EXAMINATION AND TESTING. 2023, 41(1): 40-45. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220016
    Abstract (162) Download PDF (513)   Knowledge map   Save
    It pointed out that the reason for flaw detection unqualified of 4130X steel pipe was the nonmetallic inclusions caused by secondary oxidation of open cast furnace. Take ø500 mm continuous casting blank as the object, several samples were taken from different positions of the casting blank. It was found that the oxygen content, nitrogen content, Al loss and nonmetallic inclusions in the steel in the open casting part were higher than those in other parts, which implied that the secondary oxidation in the open casting part was more serious. In addition, the nearlier to open casting part the quantity and distribution density of inclusions with length more than 5 μm. It is indicated that the effect of secondary oxidation on inclusions more then 5 μm is obviously when open casting.
  • Cause analysis on block peeling from flange of wheel
    WANG Ruijun
    PHYSICS EXAMINATION AND TESTING. 2023, 41(3): 21-27. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220049
    Abstract (145) Download PDF (512)   Knowledge map   Save
    The block peeling from the flange of rear wheel occurred when the subway wheel was used for a period of time. In order to find out the cause, some methods including chemical composition inspection, mechanical analysis, macroscopic observation of fracture and metallographic structure analysis were employed. The results showed that the block peeling from the flange of wheel was the typical characteristic of peeling caused by multisource high stress fatigue fracture. High hardness white layer martensite and the composite structure with depth up to 7 mm were the main reasons for block peeling from the flange. The composite structure on deep surface should be caused by the unreasonable quenching process. It was suggested to develop the reasonable quenching process for the flange of wheel to avoid formation of defect structures.
  • Analysis of hole defect of 2219 aluminum alloy ring
    GONG Zhongxing, ZHANG Zheng, WANG Panzhi, XIANG Chunhua
    PHYSICS EXAMINATION AND TESTING. 2023, 41(3): 16-20. https://doi.org/10.13228/j.boyuan.issn1001-0777.20220047
    Abstract (173) Download PDF (506)   Knowledge map   Save
    During the inspection of 2219 ring forgings, it was found that there were defects inside, which were about 5 mm from the inner diameter and 80 mm from the end face. The flaw detection showed that the defects were long strips with the length of about 30 mm, and the direction was parallel to the diameter direction of the forgings. In order to analyze the causes of the defects, the macrostructure, microstructure, scanning electron microscopy and energy spectrum analysis of the defective samples were studied in the laboratory. The results showed that the defects of 2219 aluminum alloy ring forging were hole defects, which were caused by the low AlZr input temperature during smelting. It reduced the diffusion rate of elements and increased the segregation of AlZr alloy phase, leading to the formation of hole defects.
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