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.

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.

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 (T_C) 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

The power supply and communication between instruments were interrupted when a certain drilling adapter fractured, which caused economic loss after drilling. The fracture cause of the adapter was determined by the analysis of macroscopic morphology, microscopic morphology, metallographic structure, chemical composition and hardness testing. The results showed that the adapter belonged to fatigue fracture. The fatigue source was located at the sharp edge defect of the long strip protrusion at the thread root where the cutting groove and thread chamfer were connected. There was a high local stress concentration at this location, and the fatigue cracks initiated and rapidly expanded under the alternating load of drilling work. In addition, the beryllium bronze material under simultaneous action of solid solution and aging treatment was sensitive to notches, weakening the grain boundaries, which was prone to formation of intergranular cracks.

In order to improve the frequent spalling failure of gearbox bearing in working process of a passenger car, the failure analysis of 42 sets of bearings due to spalling failure was conducted by scanning electron microscope (SEM),energy disperse spectroscopy(EDS) and optical microscope(OM). The results showed that there was no abnormality in SEM morphology for 92.9 % of the bearing spalling products. In addition, the element analysis, microhardness and carbide grade of products could all meet the technical requirements of GB/T 18254-2016 or internal control. The main failure causes for the product were not obviously related to of raw material quality and heat treatment, but were related to product design and lubrication environment. It was necessary to adjust the force design and oil supply mode of gearbox. After improvement according to the analysis results of failure parts, the quantity of bearing failure parts significantly was reduced by about 60%.

The leaking of some tubes in heat exchanger was observed in a secondary tower′s top condenser in one certain distillation deisobutanizer. In order to find out the failure cause and prevent the similar incidents from recurring, the chemical composition, mechanical properties, metallographic structure, and microscopic morphology of the tubes were analyzed to identify the reasons for leaking. The results showed that the heat exchanger tubes had a serious uniform corrosion and local point corrosion perforation, leading to the leaking of tubes. Moreover, the corrosion morphology had the characteristics of microbiological corrosion. Meanwhile, the large size nonmetallic inclusions in heat exchanger tubes accelerated the process of point corrosion perforation of tube wall.

The patent application of household stainless-steel sinks in China was analyzed based on the perspective of patent. The application trend, type distribution, application subjects, technical types, and research topics of household stainless-steel sink patents were sorted out. A multifunctional detection equipment for household stainless-steel sinks was designed and developed. The relevant detection experiments were conducted according to the national standard GB/T 38474-2020 Household Stainless Steel Sinks. The results showed that the multifunctional detection equipment could achieve the installation of different specifications of sinks, and could also meet the testing standards for detection of indicators such as load-bearing performance, anti-condensation coating, and drainage mechanism performance. It significantly improved the work efficiency and reduced the labor costs, and also ensured the scientificity and accuracy of testing data.

The influences of three kinds of coating, i.e., hot-dip galvanizing coating, hot-dip galvanized iron alloy coating and electroplating galvanizing coating, on the tensile properties of cold-rolled plate were analyzed in this paper. The tensile properties of IF-grade cold-rolled plate with different coatings were measured by 0.5 grade tensile tester, and the tensile properties before and after coating removal were compared. The results showed that there was no obvious difference in tensile properties before and after electroplating galvanized coating removal. The yield strength, strain hardening exponent (n value) and plastic strain ratio (r value) were different before and after hot dip galvanized coating removal. The tensile properties before and after hot-dip galvanized iron alloy coating removal were different, and the difference of r value was most significant, which reached 0.35. The surface and fracture were observed by scanning electron microscope(SEM). It was found that the tiny cracks were produced during the fracture of hot-dip galvanized iron alloy coating, which had a great impact on the measurement of r value.

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.

The surface defects in automobile stabilizer rod could lead to the performance deterioration of automobile and even cause the breaking of balance rod, which seriously affect the safety of automobile driving. The 55Cr3 wire rod produced in a certain factory was tested in one automobile parts factory, and it was found that there were some deep decarbonization defects on the surface of the rolled high wire rod. The process of controlled rolling and controlled cooling were optimized, the heating temperature of the billet in heating furnace was reduced, and the control temperature center line of soaking section was reduced from the original 1 080 ℃ to 1 020 ℃. The heating furnace atmosphere was adjusted, and the air-fuel ratio was adjusted from the original 0.75% to 0.55%. The spinning temperature of the wire rod and the running speed of the air-cooled roller were reduced, and the speed of the entrance section was increased from 0.12 m/s to 0.13 m/s. The cascade increase of the roller speed in different proportions was implemented, and the cooling speed in the phase change zone was appropriately increased. Finally, the wire rod without decarbonization defect was obtained, which could meet the product performance requirements for customer.

Monte Carlo method is a distributed propagation method based on random sampling for probability distribution. Monte Carlo method and GUM method were used to evaluate the uncertainty in the determination of elastic modulus of titanium alloy by suspension wire coupled resonance (dynamic method) specified in GB/T 22315-2008 Metallic materials-Determination of modulus of elasticity and Poisson′s ratio. According to the evaluation results of Monte Carlo method, the results of single test could be expressed as (123.6±1.6) GPa with coverage factor of k=2. According to the evaluation results of GUM method, the results of single test could be expressed as (123.6±1.7) GPa,k=2. The deviations of the results, expanded uncertainty, the upper and lower limits of the confidence interval obtained by the above two methods were +0.0, 0.2, +0.2, and 0.1 GPa, respectively. The deviations were less than the numerical tolerance (0.5 GPa). The results of the above two methods were consistent.