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2021 Vol. 56 No. 2
Published: 2021-02-15
Technical Reviews
Raw Material and Ironmaking
Steelmaking
Metal Forming
Materials
Environmental Protection and Energy
Technology Exchange
Expert Forum
Expert Forum
1
QIAN Jia-shu
Review on world steel industry development in contemporary and “Chinese Approach” proposal
In order to explore the future development of China′s iron and steel industry,the relationship between apparent steel consumption per unit GDP,apparent steel consumption per capita and GDP per capita in 34 world economies including China,the United States,Japan,Germany,France,South Korea and Iran, etc. from 1970 to 2018 was statistically analyzed. The results show that the apparent consumption of steel per unit GDP did not increase with the growth of GDP per capita. On the contrary,there was a decreasing power function correlation tending to be balanced. Low apparent consumption of steel per unit GDP was totally enough to create a high GDP per capita. Thus,there was no need to blindly looking for increase of high production,which leaded to a strong "Identity". While the correlation between apparent steel consumption per capita and GDP per capita showed a strong "Dissimilarity" as different economies could develop in 3 different types of interrelationship. At the moment,the developed countries were all in unilateral decline type. On this basis,4 kinds of peak steel production approaches were forecasted,and the "Chinese Approach" is thus put forward.
2021 Vol. 56 (2): 1-11 [
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273
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12
WANG Xin-dong
Planning and design of HBIS Group Tangsteel new district with goal of "Green, Intelligent and Brand"
The HBIS Group Tangsteel New District is the concrete practice implemented by HBIS Group under the important directive spirit of "resolutely eliminate excess production capacity, actively adjust the structure and accelerate the conversion of kinetic energy" made by General Secretary Xi Jinping and in response to the structural adjustment of iron and steel industry in Hebei Province. With the construction goal of "green, intelligent and brand", the project is intended to take the continuity, simplification and compactness of material flow, energy flow and information flow as the direction and apply the latest dynamic precise design, integration theory and process interface technology of steel plant, as well as more than 230 cutting-edge new technologies and more than 130 green steel manufacturing technologies, covering the whole process flow of raw materials, coking, sintering, pelletizing, blast furnace, converter and steel rolling in an effort to build the HBIS Group Tangsteel New District into a world-class modern coastal dream works with environmental protection, cutting-edge technology, intelligent production line, efficient process, high-end products and reasonable investment.
2021 Vol. 56 (2): 12-21 [
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371
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Technical Reviews
22
ZHOU Chao-gang, YANG Hui-ze, AI Li-qun, WANG Shu-huan, HU Jin-zhen, CHEN Hu
Research status and prospect of recycling technology of converter slag containing phosphorus
In order to realize the efficient recycling of converter phosphorus containing steel slag, the production status,composition,source,and migration and enrichment mechanism of phosphorus,mineralogical structure,and research status of dephosphorization technology of converter slag are systematically analyzed. On this basis,through the discussion and summary the recycling technology of converter phosphorus-containing steel slag,it shows that the current steel slag recycling technology has the disadvantages of low phosphorus resource utilization efficiency and large energy consumption of steel slag. Therefore,it is an inevitable trend to determine the utilization mode according to the phosphorus content of steel slag and reduce the energy loss of steel slag as much as possible in the recycling process. Based on the previous research,the prospect of efficient recycling of low phosphorus slag and high phosphorus slag is further prospected,so as to provide theoretical basis and technical reference for iron and steel enterprises to improve the recycling rate of converter phosphorus-containing steel slag and reduce the production cost of raw materials.
2021 Vol. 56 (2): 22-39 [
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366
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40
LI Qi, CHEN Zheng-zong, JIANG Xin-liang, LIU Zheng-dong, ZUO Liang
Development and engineering manufacture technology of 9%-12% Cr high and medium pressure rotor material
Due to the particularity of dimensions and working condition,the high and medium pressure rotor forgings have been the major critical component with milestone significance in the process of technological development of ultra-supercritical units. Nowadays,9%-12%Cr martensitic heat-resistant steel is widely used to produce the high and medium pressure rotor forgings for 600-620 ℃ ultra-supercritical units. The developing history of 9%-12%Cr heat-resisting material for the high and medium pressure rotor forgings in recent 60 years was comprehensively discussed. For high and medium pressure rotor forgings with different service temperatures,the material selection, chemical composition and strengthening mechanism of forgings are emphatically introduced,and the difficulties and key points of smelting process,forging process and heat treatment process in engineering manufacturing process are briefly described,which provides guidance for the engineering manufacturing of high and medium pressure rotor forgings of ultra-supercritical units at 600 ℃ and above.
2021 Vol. 56 (2): 40-49 [
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Raw Material and Ironmaking
50
YI Zheng-ming, QIN Jia-zhuo, JIANG Zhi-wei, QIN Qing-wei, SHAO Hui-jun, DU Dong
Influence of MgO on high basicity high alumina sinter
The increase of the proportion of high Al
2
O
3
content iron ore fine in iron and steel enterprises has brought about a series of problems such as the increase of the viscosity of blast furnace slag and the difficulty of the separation of slag and iron. The effect of increasing MgO content on the technical and economic index, the cold strength, and metallurgical properties of high basicity and high alumina sinter was studied through the sinter pot test. Nova400 NanoSEM field emission scanning electron microscope was used to analyze the microstructure of the sinter. The experimental results show that when the mass percent of MgO in the sinter with high alkalinity and high aluminum increases from 1.72% to 2.49%, the vertical sintering speed decreases by 4.38 mm/min, the utilization coefficient decreases by 0.51 t/(m
2
·h), and the low-temperature reduction degradation index increases by 6.7%. When the mass percent of MgO in the sinter is 2.11%, the drum index and the reducibility index are the highest, reaching 61.93% and 86.39% respectively. Mg
2+
is mainly solid dissolved in the magnetite lattice and replaces Fe
2+
, and the mass fraction of the replacement reaches up to 3.64%. The generated magnesium-containing magnetite inhibits the phase transition from Fe
3
O
4
to Fe
2
O
3
oxidation process in the sinter cooling process, which reduces the generation of secondary hematite and is conducive to improving the low-temperature reduction degradation performance of the sinter. The research results can provide theoretical guidance and reference for improving the properties of high-basicity and high-alumina sinter and adjusting the fluidity of blast furnace slag.
2021 Vol. 56 (2): 50-56 [
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57
ZHOU Heng, XU Kun, YAO Shun, KOU Ming-yin, WU Sheng-li
Numerical simulation of injection of COREX decarbonized top gas to blast furnace
COREX decarbonized top (CEG), as a high-quality hydrogen-rich gas, directly injected into blast furnace can effectively reduce the fuel consumption. A static model of blast furnace operation of CEG was developed. The effects of CEG injection on the raceway adiabatic flame temperature (RAFT), the amount and composition of bosh gas, the shape of raceway, the direct reduction degree, and the coke saving effect were studied. Furthermore, the acceptable quantities of CEG after increasing the blast temperature as a thermal compensation measure was investigated. The results showed that under no thermal compensation, with the increase of CEG injection, the RAFT decreases but the volume of bosh gas increases. The direct reduction degree decreases with the increase of CEG injection. Based on the standard of maintaining the RAFT and volume of bosh gas, when the blast temperature is increased by 30, 60, 90 ℃, the corresponding suitable CEG injection volume is 45.4, 85.5, 123.3 m
3
/t, respectively. After thermal compensation, with the increase of CEG injection, the blast volume decreases but the oxygen enrichment rate increases. The CO and H
2
contents in the raceway increased with the increase of the injection volume of CEG. For every 10 m
3
/t increase of CEG injection volume, the reducing content in bosh gas is increased by 0.46 %, the direct reduction degree decreases by 0.006, and the coke is saved by 1.48 kg/t.
2021 Vol. 56 (2): 57-62 [
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Steelmaking
63
WEI Guang-sheng, DONG Jian-feng, ZHU Rong, HAN Bao-chen
Effect of ladle bottom blowing on RH dehydrogenation and inclusions
The ladle bottom blowing in the RH(Ruhrstahl Heraeus) vacuum refining process has received extensive attention in recent years as a way to improve the refining effect. In order to study the influence of ladle bottom blowing on actual production. The effect of ladle bottom blowing on dehydrogenation and inclusions in the RH vacuum refining process was studied through industrial production experiments. The results show that increasing the bottom blowing of the ladle optimizes the flow and mixing of the molten steel inside the ladle, increases the collisional growth rate of inclusions and the average size of the inclusions, improves the dehydrogenation effect, and increases the dehydrogenation rate, especially the dehydrogenation rate at higher hydrogen mass percent. When the bottom blowing flow is 30 and 50 L/min , the vacuum time required to remove hydrogen to 0.000 2% is reduced by 5.58% and 16.40%, and the dehydrogenation rate is increased by 9.76% and 19.51% at this time. In addition, the increase in the number density of inclusions decreased from 64.2% to 49.7% and 13.0%, and the increase in the average area of inclusions increased from 17.34% to 40.98% and 53.37%.
2021 Vol. 56 (2): 63-68 [
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267
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69
ZHANG Yin, WANG Lin-zhu, LI Jun-qi, YANG Shu-feng, CHEN Chao-yi
Comparison on non-metallic inclusions in OCTG steel from home and abroad
In order to improve the performance of OCTG (oil country tubular goods) steel, the composition and morphology of inclusion were observed by scanning electron microscope. The particle size distribution, inter-surface distance, and distribution of inclusions were analyzed. The evolution of inclusions during the cooling process was analyzed based on the equilibrium solidification model with FactSage software. The collision rate of inclusions in OCTG steel was estimated based on the inclusion collision number balance model. The results indicate that there were mainly CaS with encapsulated Spinel inclusions in Japanese OCTG steel, and CaO with encapsulated Spinel and pure Spinel inclusions in Chinese OCTG steel, respectively. In comparison with the inclusions in Chinese OCTG steel, the inclusions in Japanese OCTG steel are less and smaller and distribute more uniformly. The number density of inclusions is 7.5/mm
2
in Japanese OCTG steel and 28.3/mm
2
in Chinese OCTG steel. The largest inclusions are less than 5 μm in Japanese OCTG steel, which reaches 20 μm in Chinese OCTG steel. The calculated results about inclusion evolution during the cooling process based on FactSage are in good agreement with experimental results. The collision rate of inclusions in Chinese OCTG steel is two orders of magnitude higher than that in Japanese OCTG steel.
2021 Vol. 56 (2): 69-75 [
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76
ZENG Yao-xian
Cleanness control of sulfur bearing gear steel 20CrMnTiH
In order to reduce the boron content and inclusions of gear steel,in view of the high purity requirement of high-quality sulfur gear steel, the FactSage was used to calculate the chemical reaction equilibrium between B
2
O
3
and Al, the iso-activity diagram of gear steel, and the ternary phase diagram of MgO-Al
2
O
3
-SiO
2
. The calculation results show that the higher content of Al in the molten steel can reduce the B
2
O
3
remaining in the molten steel. Increasing the content of Al
2
O
3
in the refining slag and increasing the content of MgO in the tundish dry material with decreasing the content of SiO
2
can improve the cleanness of the molten steel of gear steel. When the above countermeasures were applied to industrial producing, the
w
(T[O]) of gear steel were less than 0.001 2%, the contents of B of gear steel were less than 0.000 5%, the levels of A-type inclusion were less than 2.0 and those of other type inclusions were less than 1.0 in gear steel. The qualification rate was improved from 71.5% to 100%. There was no large particle inclusion in the steel. The cleanness of sulfur bearing gear steel was significantly improved after process optimization.
2021 Vol. 56 (2): 76-81 [
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82
KANG Ji-bai, WANG Wei-ling, LUO Teng-fei, LUO Sen, ZHU Miao-yong
Internal quality control of 160 mm×160 mm square billet of 20CrMnTi steel with EMS
In order to improve the severe internal quality problems in continuously cast 160 mm×160 mm billets of 20CrMnTi, industrial tests to optimize synergistically processing parameters of mold electromagnetic stirring(M-EMS) and final electromagnetic stirring(F-EMS) were carried out. The effects of technical parameters on the internal quality of 20CrMnTi billets were analyzed in detail through the chemical etching for the macrostructure and via measurements for the carbon contents. Besides,an infrared thermal image instrument was used to test the billet surface temperature,and ANSYS software was subsequently utilized to calculate the temperature variation during the solidification of the billet. Accordingly,the thickness of the liquid pool at F-EMS was obtained. The results show that the initial locations of columnar-to-equiaxed transition(CET) zone at the inner arc and outer arc sides are fixed around 42 and 28 mm,respectively,and they have only a little change within the range of M-EMS current intensity from 240 to 260 A. There exists negative segregation of carbon at 10 mm below the billet surface. However,carbon enriches in front of the CET zone and appears to be positive and negative segregation alternately in the solidification center. The negative segregation of carbon in the vicinity of the solidification center is positively correlated with the stirring intensity of M-EMS and F-EMS. According to the experimental results,the optimal parameters of M-EMS and F-EMS are 250 A/4.0 Hz and 300 A/7.0 Hz,respectively. Additionally,the liquid pool’s thicknesses vary from 66.2 mm at the entrance of F-EMS stirrer to 60.6 mm at the outlet of F-EMS stirrer and the corresponding solidification ratio ranges from 86.6% to 88.7%,which manifests that the current F-EMS implemented position is proposed.
2021 Vol. 56 (2): 82-92 [
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Metal Forming
93
HUANG Jin-lei, ZANG Yong, GAO Zhi-ying
Influence of process parameters on vibration natural characteristics of hot rolling mill
The vibration problem of rolling mill is the main cause of strip thickness difference,surface scratch or vibration pattern. In addition,vibration can cause fatigue damage of equipment parts,and even cause instability vibration due to process reasons,which will endanger the production safety of the system. It is very important to master and understand the natural frequency and vibration characteristics of rolling mill system,which is the basic condition of vibration analysis. Strong vibration occurred on F2 stand of hot continuous rolling line in a steel plant when rolling thin products. In order to better identify the type of mill vibration and suppress the mill vibration,it is necessary to conduct a comprehensive analysis on the natural modal characteristics of the rolling mill system. Considering the vibration of horizontal,torsional and vertical system,and considering the coupling effect of strip and rolling mill system,an 11 degree of freedom vibration model of hot rolling mill is established. The natural modal characteristics of the rolling mill system without strip steel are analyzed,and the sensitivity of inertia parameters and elastic parameters to the natural modal characteristics of the rolling mill system is analyzed. At the same time,the influence of process parameters,such as front and back tension,inlet thickness,exit thickness,friction coefficient and deformation resistance on the natural characteristics of the rolling mill system is analyzed. The results show that the strip and rolling mill are coupled to form a variable structure system. The natural characteristics of the system vary with different process parameters. The process parameters mainly affect the natural characteristics of the system by changing the 4th and 10th modes. The influence of different process parameters on the natural characteristics of rolling mill system is different,and the influence of inlet thickness is the most significant. The system natural frequency can be improved by changing process parameters. The guidance for the identification of rolling mill vibration types and vibration suppression was provided.
2021 Vol. 56 (2): 93-98 [
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99
LIANG Peng-wei, DONG Zhi-kui, JIAO Yun-jing, XIE Xing-hua
Calculation model of steel coil temperature field in annealing process of full hydrogen bell furnace
Aiming at the phenomenon of product quality problems due to the large temperature difference between the hot spots and cold spots of the steel coil,and the long holding time during the annealing process of a full hydrogen bell annealing furnace unit of a certain plant,the heat transfer mathematical model of the unit in the annealing process is established. A correction factor is added to the thermal conductivity and convection heat transfer coefficient of the steel coil,and the processing method of each coefficient is studied. Through a large number of actual data corrections,a better correction factor is obtained. Using the finite difference method to solve the mathematical model,compared with the measured data,the results show that the error of 92% of the temperature points in the calculated value of hot spot temperature is below 5.12%,and the error of 90% of the temperature points in the calculated value of cold spot temperature is below 5.05%. This shows that the mathematical model and calculation method are reliable and can be used for predictive analysis of the temperature field during the annealing process of the plant's full-hydrogen bell furnace unit,which has certain guiding significance for the optimization of the annealing schedule.
2021 Vol. 56 (2): 99-104 [
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Materials
105
KAN Li-ye, YE Qi-bin, TIAN Yong, WANG Zhao-dong, WANG Guo-dong
Tempering process of Cu-NiAl nano co-precipitation strengthened steel
In order to study the microstructure and mechanical properties of Cu-NiAl nano co-precipitation strengthened steel tempered at different processes,OM and TEM were used to analyze the microstructure of the experimental steel tempered in the range of 300-650 ℃,and the mechanical properties were discussed. The results show that bainitic ferrite lathes began to coarsen and gradually transformed into equiaxial ferrite,and there were nanoscale precipitates in the matrix at tempering temperature 300-550 ℃. During tempering at 600-650 ℃,lath structure completely transformed to equiaxial ferrite,and nanometer precipitates gradually grew and coarsened. The optimum tempering temperature range for the Cu-NiAl nano co-precipitation strengthening steels was 550-600 ℃.The yield strength was 855-917 MPa,the impact energy tested at -40 ℃ is 77-86 J,and the comprehensive mechanical properties were good.
2021 Vol. 56 (2): 105-109 [
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110
CHEN Guang-hui, XU Guang, HU Hai-jiang, LIU Man, CHEN Xin
Controlling mechanism of retained austenite in a 1.6 GPa grade medium-carbon high-strength bainitic steel
In order to investigate the changing law of the volume percent of retained austenite in a medium-carbon bainitic steel under different isothermal conditions,X-ray diffraction measurement,thermalmechanical simulation experiment and scanning electron microscope were utilized to analyze the effects of austempering on the volume percent of retained austenite and microstructure. The results indicated that the final volume percent of retained austenite was affected by bainite and martensite transformation. The amount of bainite transformation influenced the amount and chemical stability of untransformed austenite,therefore affecting the amount of subsequent martensite transformation and the final volume percent of retained austenite. Moreover,the volume percent of retained austenite first increased with transformation temperature due to less bainite transformation (300-350 ℃) and then decreased because of more martensite transformation (350-400 ℃).
2021 Vol. 56 (2): 110-116 [
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117
ZHAO Kai, YANG Zhong-min, WANG Wen-tao, CHEN Ying, CAO Yan-guang, LI Zhao-dong
Effect mechanism of carbon content on properties of Fe-15Mn-4.5Si-10Cr-5Ni-C-based shape memory alloy
In order to obtain shape memory alloy with excellent shape memory performance by regulating carbon content,microstructure,mechanical properties and shape memory effect of Fe-15Mn-4.5Si-10Cr-5Ni-C-based alloys with three different carbon contents in solution aging state were studied. The results showed that the shape memory effect of Fe-15Mn-4.5Si-10Cr-5Ni-(0.05~0.2) C alloys increased first and then decreased with the increase of carbon content. It caused by several reasons. One is that the interstitial solution strengthening of carbon atoms and the precipitation strengthening of second phase carbides increase the strength of austenitic matrix with the increase of carbon content,which inhibits the occurrence of irreversible plastic deformation. In other word,strengthening of austenitic matrix facilitates the stress-induced martensitic transformation of the alloys under stress. On the other hand,the complete solution temperature increases with the increase of carbon content. Then,the relatively large austenite grains obtained after solid solution treatment reduced the strength of austenitic matrix. In addition,with the increase of carbon content,the temperature of martensitic phase transformation point (M
ε
s
) decreased,and the strain-induced phase transformation process was inhibited,which was not conducive to the shape memory effect. Under the influence of different mechanisms,the shape memory effect of the experimental alloys in the solution aging state with a carbon mass percent of 0.091 8% was the best.
2021 Vol. 56 (2): 117-125 [
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230
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126
SU Cheng, FENG Guang-hong, YUAN Xiao-ming, WANG Shao-bing, LI Zhao
Development of low alloy NM400 wear-resistant steel strip based on 2 250 mm hot continuous rolling mill
In order to develop low-alloy high-strength thin-gauge wear-resistant coils with cost advantages,the current domestic advanced 2 250 mm hot continuous rolling mill process characteristics are adopted,after two-stage controlled rolling,three types of front concentration,front dispersion and segment cooling are used respectively controlled cooling process,systematically studied the effect of different cooling rates and cooling paths on the microstructure and mechanical properties of the product at the same start cooling temperature. The results show that the use of segmented cooling in the three cooling modes is more reasonable,and the specific key control process the intermediate temperature is 650 ℃,the waiting time is 10 s,the two-stage cooling rate is 40 ℃/s,and the coiling temperature is 170 ℃. The microstructure of products at room temperature is comprise mainly bainite and little of lath martensite and ferrite,which has the advantages of high strength and toughness and low yield ratio,the various performance meet the requirements of GB/T 24186—2009 and user conditions.
2021 Vol. 56 (2): 126-131 [
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229
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132
HOU Xiao-ying, SUN Wei-hua, WANG Ye-qin, JIN Guang-yu, CAO Guang-ming, REN Dong
Microstructural control and mechanisms of strength-ductility enhancement for 1.0 GPa grade I&QP steel
In order to investigate the microscopic morphological characteristics and the mechanisms of strength-ductility enhancement of I&QP steel,the characteristics for microstructures and mechanical properties and the effect on strength and plasticity were analyzed by using different annealing processes. The results indicated that the final mixed microstructure was controlled which was composed of "lath-shaped clusters" bainites with different orientations,a small amount of ferrite whose grain size was less than 2.5 μm,as well as lamellar retained austenites,when the needle-like bainite was controlled for the initial hot-rolled microstructure,whose volume percent was more than 85% and fine grain size was in the range of 3-5 μm. The volume pecent of "lath-shaped clusters" bainites was more than 70%,and the volume percent of lamellar retained austenites was more than 14.5%. When the intercritical heating temperature was decreased to 850 ℃ properly,the grain size of I&QP steel could be refined obviously,and the ratio of large misorientation angle was increased to 60.2%. Under the combined action for the mechanisms of strength-ductility enhancement which including the phase transformation,grain refinement,phase precipitation and dislocations,the tensile strength was more than 1.0 GPa,the product of tensile strength and ductility was reached to 30.2 GPa·%,and the expanding rate was up to 62%.
2021 Vol. 56 (2): 132-138 [
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400
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139
DU Chong-yang, SUN Bin, CHENG Lei, GAO Wei, ZHANG Jing-ke
Oxidation behavior of steel with low Cr content under water vapor atmosphere
In order to investigate the oxidation behavior of low Cr element content steel under water vapor conditions, a thermogravimetric analyzer (TGA) was used to carry out high-temperature oxidation experiments for 5Cr and 10Cr steel in a water vapor atmosphere. The mechanism of surface oxidation of low Cr content steel under water vapor atmosphere was studied by the metallographic microscope and XRD. The results show that the existence of water vapor on the surface of the matrix will produce holes and cracks, which becomes a favorable channel for the internal diffusion of water vapor. With the increase of chromium content, the higher the required temperature of the transformation from linear law to parabola law. The iron oxide layer of the sample is composed of the outer oxide layer and the inner oxide layer. The outer oxide layer is mainly Fe
2
O
3
and Fe
3
O
4
, the inner oxide layer contains a large amount of Cr oxides. When the oxidation temperature is above 1 000 ℃, the weight gain of the two sheets of steel is close, mainly because the Cr elements in the steel are oxidized to form Cr
2
(OH)
2
and Cr (OH)
3
, which results in the failure of the oxidation resistance of the inner layer.
2021 Vol. 56 (2): 139-146 [
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223
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Environmental Protection and Energy
147
HAN Yang, DONG Jing, LI Jie, ZHANG Yu-zhu, SHI Zhen-yang
Visual analysis and application of high temperature melting behavior of iron tailings
The content and melting point of SiO
2
in iron tailings from metallurgical solid waste in Eastern Hebei Province are the highest. In order to investigate the dissolution behavior of solid iron tailings in molten blast furnace slag,SiO
2
,the main component of iron tailings,was studied. A modified CCD video camera system with a magnifying effect is introduced in the visual inspection of the high temperature melting process of SiO
2
particles,which is used to obtain the sequence images of the melting process in real-time. Considering the continuity of the quenching and tempering process,the convolution neural network algorithm is used to accurately track the moving object (SiO
2
particles), and the track of the center of mass of the target in the sequence images is determined. The SiO
2
melting process is directly described by the coordinate translation transformation theory. The contour and area of the solid part of SiO
2
were determined by hierarchical clustering intelligent algorithm. The perimeter,area,and other characteristic parameters of unmelted SiO
2
particles in the sequence images were extracted. The melting rate of SiO
2
particles at high temperatures was estimated by the least square fitting algorithm and dimensional analysis. The visual effect of the high temperature melting behavior of SiO
2
was verified by predicting 100% hit rate of the endpoint (complete melting). Dynamic heating during quenching and tempering is realized. According to the real-time mathematical model of SiO
2
particle melting rate and thermal compensation,the collaborative control chart of iron tailings ratio,slag system temperature,slag flow temperature, and heat supplement is obtained by coupling the two models,and the accurate thermal dynamic intelligent compensation of slag cotton preparation process is realized.
2021 Vol. 56 (2): 147-154 [
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248
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612
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Technology Exchange
155
WANG Di, YANG Shu-feng, QU Jing-long, DU Jin-hui, AN Teng, HUANG Yan-cheng
Distribution of inclusions on surface of GH4169 ESR ingot
Electroslag remelting is the middle link of the "triple" smelting process of the GH4169 superalloy. The surface quality of electroslag ingot is of great significance to improve the purity of consumable ingot. The surface quality can be improved by using an appropriate turning amount. Scanning electron microscopy with energy-dispersive spectroscopy,Image Pro Plus software,and JMatPro software were used to systematically explore the distribution of inclusions on the surface of the electroslag ingot,and to develop a more suitable turning range. The results showed that composite inclusions with Ti (C,N) and MgAl
2
O
3
as the core were formed in the electroslag ingot. With the location of the sample gradually away from the edge of the ingot,the amount of inclusions was reduced from 5 233 to 3 684/mm
2
and then stable fluctuation in the range of (3 650±30)/mm
2
;the average size distribution of inclusions was reduced from 7.7 to 4.9 μm and then stable fluctuation in the range of (4.3 ± 0.1) μm. According to the distribution of inclusions in the surface area,the suitable turning range of electroslag ingot is 18-24 mm. The results of industrial experiments show that the new cutting range can improve the surface quality of electroslag ingot after machining.
2021 Vol. 56 (2): 155-161 [
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465
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