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  Analysis on friction and wear properties of materials for circular gear of harmonicgear reducers Shao Zhuhao, Yang Dawei, Wu Yongjin, Liu Zhao, Zhao Liang Heat Treatment of Metals    2024, 49 (1): 47-52.   doi:10.13251/j.issn.0254-6051.2024.01.007 Abstract （54）      PDF （3885KB）（225）       Knowledge map    Friction behaviors of two nodular cast irons (QT1 and QT2) and 40Cr steel used for domestic circular gear were studied by quantitative analysis of alloy composition, microstructure and wear resistance. The results show that for the QT1 and QT2 cast irons, the matrix is composed of pearlite, retained austenite and acicular ferrite, while the spheroidal graphite has very high nodularity and fine size. The worn positions of the QT1 and QT2 cast irons are concentrated with small fluctuations, and the maximum worn surface depths are 3.7 μm and 2.6 μm respectively. The wear morphologies of the 40Cr steel are furrows with varying depths and large fluctuations, and the maximum depth is 7.6 μm. Compared to the 40Cr steel, the QT1 and QT2 cast irons have excellent wear performance and lower friction coefficient. Domestic harmonic reducer enterprises can use nodular cast iron as circular gear material instead of the 40Cr steel. Reference | Related Articles | Metrics

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  Hot deformation behavior and microstructure evolution of TC11 titanium alloy Lü Xuechun, Zhao Wenge, Yuan Mingrong, Li Heng Heat Treatment of Metals    2023, 48 (5): 279-282.   doi:10.13251/j.issn.0254-6051.2023.05.044 Abstract （96）      PDF （2582KB）（240）       Knowledge map    Deformation behavior and microstructure evolution of the TC11 titanium alloy at high temperatures were investigated. The results show that the flow stress of the alloy decreases as the deformation temperature increases and the strain rate decreases during deformation, and the degree of softening of the flow stress increases as the strain rate increases. By analysis of the processing map at true strain of 0.6, the highest energy dissipation rate is found at 940 ℃ and 0.001 s-1 and reaching 0.71. The plastic instability zone is found in the range of 920-930 ℃ and 0.9-10 s-1. The dynamic recrystallization of the α-phase during hot deformation of the TC11 titanium alloy is promoted by increase of the strain rate, the deformation volume and the deformation temperature. Reference | Related Articles | Metrics

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  Effect of subcritical heat treatment on microstructure and properties of high chromium cast irons Yuan Zhizhong, Liu Haiming, Ju Yulin, Chen Lu, Niu Zongran, Wang Zhiyuan, Cao Fuyang, Cheng Xiaonong Heat Treatment of Metals    2024, 49 (10): 1-7.   doi:10.13251/j.issn.0254-6051.2024.10.001 Abstract （244）      PDF （4765KB）（173）       Knowledge map    Aiming at the problem of high energy consumption in conventional quenching and tempering process of high chromium cast irons, the subcritical heat treatment tests of three kinds of high chromium cast irons were carried out. Moreover, the effect of the process on the microstructure, hardness and surface wear resistance was studied. The results show that the microstructure of high chromium cast irons is primarily composed of retained austenite, M7C3 carbide, (Fe, Cr)23C6 carbide, Mo2C carbide and pearlite when subjected to holding temperatures ranging from 500 ℃ to 650 ℃ for 1 h to 14 h. A peak value in hardness is observed for the three high chromium cast irons when holding at 550 ℃ to 600 ℃ for 6 h to 12 h, with the highest peak hardness being 57.4 HRC. The hardness is most significantly influenced by the Mo element. During the insulation process, the pearlite phase transformation of austenite is promoted by the precipitation of secondary carbides in high chromium cast irons. The effects of pearlite transformation strengthening and precipitation strengthening of secondary carbides gradually decrease with prolonged holding time. The eutectic high chromium cast iron with the highest carbon content exhibits the best wear resistance when holding at 600 ℃ for 8 h. It can be seen that the first step to improve the wear resistance of high chromium cast irons is to increase the amount of eutectic carbides, and then to add elements such as Mo to enhance the precipitation strengthening effect. Reference | Related Articles | Metrics

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  Design and implementation of materials database for heat treatment process simulation Zhang Lunfeng, Wang Zhihan, Zhao Junyu, An Kang, Xu Jun, Gu Jianfeng Heat Treatment of Metals    2023, 48 (9): 247-252.   doi:10.13251/j.issn.0254-6051.2023.09.042 Abstract （72）      PDF （3415KB）（212）       Knowledge map    Material parameters are the crucial data support in heat treatment process simulation. However, at present, there is a lack of relevant material databases in China, and a few existing databases have problems such as low data accuracy, poor integrity, and inability to share data, they only distinguish materials based on chemical composition, which cannot meet the parameter requirements of heat treatment process simulation. Therefore, a data structure focusing on chemical composition and microstructure was designed, and an online special material database was also independently developed. The database optimizes the data storage structure according to the characteristics of material parameters required for heat treatment process simulation. Adopting B/S architecture design realizes data sharing and improves the convenience of data use. Furthermore, by using data mining technology, the database introduces four machine learning algorithms: multivariable linear regression, Bayesian linear regression, decision tree, and random forest, and establishes an innovative data extraction mechanism. The effective data extraction strategy can be determined through the application analysis of existing data, and then the actual data requires at present can be obtained, which preliminarily solves the problem of data missing currently, and strongly supports the development of heat treatment process simulation. Reference | Related Articles | Metrics

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  Effect of solution and aging treatment on impact properties of ZL108 aluminum alloy Tan Guoyin Heat Treatment of Metals    2023, 48 (5): 291-293.   doi:10.13251/j.issn.0254-6051.2023.05.047 Abstract （46）      PDF （1272KB）（227）       Knowledge map    Impact properties of the ZL108 aluminum alloy after solution aging treatment were studied by means of OM, SEM and impact testing machine. The results show that the as-cast microstructure is mainly composed of α solid solution, coarse eutectic silicon and bulk primary silicon. After solution and aging treatment, the precipitated phase is fine and evenly distributed, with a morphology similar to short rod or coral shaped, which can better pin dislocations and help improve the impact properties of the material. The non-equilibrium distribution of elements in the as-cast specimens results in the production of a large amount of refractory eutectic silicon and bulk primary silicon. After solution and aging treatment, the precipitated phase particles continue to break under high temperature, and most of them are remelted into the matrix. The remaining precipitate particles have smaller sizes, which can better coordinate the deformation of the matrix and improve the impact properties of the specimen by 6.6 times. Reference | Related Articles | Metrics

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  Effect of austenitization temperature on microstructure and mechanical properties of 40CrMnSi2Mo steel under air cooling Yu Linran, Liu Geng, Yang Zhuoyue, Su Jie, Ning Jing, Ding Yali Heat Treatment of Metals    2024, 49 (12): 1-8.   doi:10.13251/j.issn.0254-6051.2024.12.001 Abstract （179）      PDF （5846KB）（158）       Knowledge map    Effect of austenitization temperature (875-975 ℃) on the microstructure and mechanical properties of the novel Cr-Mn-Si series high strength medium carbon low alloy 40CrMnSi2Mo steel under air cooling condition was studied by means of optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and laser scanning confocal microscope (LSCM). The results show that when austenitized at 875 ℃ and 900 ℃, the microstructure is dominated by martensite with a small amount of the undissolved precipitates (NbC). The prior austenite grains are fine and stable. The tensile strength is 1997 MPa and 2003 MPa, the elongation is 11.0% and 12.0%, and the fracture toughness is 70.3 MPa·m1/2 and 73.6 MPa·m1/2, respectively. When austenitized at 975 ℃, the solubility of NbC increases and the pinning effect decreases. The growth of austenite grain size decreases the thermal stability so that the coarse bainite/martensite multiphase is obtained under air cooling. The tensile strength is 1980 MPa, the elongation is 10.5%, and the fracture toughness is only 77.6 MPa·m1/2. The effect of the austenite grain refinement on the strength and toughness of the 40CrMnSi2Mo steel is not obvious. The fine bainite/martensite multiphase can be obtained after austenitizing at 950 ℃. The mechanical properties achieve an excellent combination, with the tensile strength of 2040 MPa, the elongation of 12% and the fracture toughness of 86.6 MPa·m1/2. Reference | Related Articles | Metrics

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  Evolution of microstructure and macrotexture of 3.1%Si oriented silicon steel Liu Yongzhen, Dong Lili, Liu Baozhi, Zhang Hao, Ma Yonglin Heat Treatment of Metals    2023, 48 (9): 238-241.   doi:10.13251/j.issn.0254-6051.2023.09.040 Abstract （80）      PDF （2289KB）（179）       Knowledge map    Microstructure and macroscopic textures of 3.1%Si oriented silicon steel during first cold rolling, decarburizing annealing, second cold rolling, high temperature annealing and tensile leveling annealing were analyzed by means of Zeiss microscope, X-ray diffractometer and other testing instruments. The results show that microstructure of the oriented silicon steel is ferrite. The average grain size is 10.23 μm after first recrystallization during decarburizing annealing, and reaches 2.0 cm after second recrystallization during high temperature annealing, and grows to 2.3 cm with increasing of uniformity after tensile leveling annealing. The main texture type of the oriented silicon steel after decarburization annealing is γ fiber texture, with a small amount of Goss texture {110}<001>. After high temperature annealing, the texture type is mainly Goss texture {110}<001>. After tensile leveling annealing, the Goss texture reaches the strongest and sharpest degree. Reference | Related Articles | Metrics

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  Effects of rare earth elements Ce and Y on high temperature oxidation behavior of JG4246A alloy Chen Chonglin, Wang Jun'an, Yu Jianbo, Tu Yuguo, Zhang Meng, Li Mengli Heat Treatment of Metals    2023, 48 (5): 78-82.   doi:10.13251/j.issn.0254-6051.2023.05.013 Abstract （59）      PDF （2724KB）（193）       Knowledge map    In the secondary generation superalloy JG4246A, rare earth elements Ce and Y were added to obtain four kinds of tested alloy ingots with addition of 0.012Ce (mass fraction, %, the same below), 0.017Ce, 0.034Y and 0.061Y, respectively. The effects of Ce and Y on high temperature oxidation resistance of these alloys at 1100 ℃ were studied. The phase composition and the morphology of oxidized surface were analyzed by means of X-ray diffractometer (XRD) and scanning electron microscope (SEM). The results indicate that the oxidation mass gain of the JG4246A alloy can be reduced by adding rare earth elements during the isothermal oxidation process at 1100 ℃ in air, and the oxidation kinetics of the JG4246A alloys conforms to parabolic law. Compared to the rare earth element Y, Ce has a more significant effect on slowing down the high temperature oxidation rate of the JG4246A alloy. The addition of rare earth elements does not change the surface morphology of the oxide film, but the spinel oxide makes the oxide film more compact, which can inhibit the outward diffusion of cations and reduce the oxidation reaction rate, thus improving the oxidation resistance at high temperature. Reference | Related Articles | Metrics

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  Variant selection of α phase in β-type Ti-15Mo alloy Ren Cheng, Min Xiaohua, Fei Qi Heat Treatment of Metals    2024, 49 (9): 1-10.   doi:10.13251/j.issn.0254-6051.2024.09.001 Abstract （128）      PDF （5708KB）（132）       Knowledge map    SEM and EBSD were used to investigate the variant selection behaviour of the α phase in the β matrix and at the β grain boundaries in the Ti-15Mo alloy after solution treatment and aging. The results show that the solution treated specimen consists of single β grains without any preferred orientation. In the solution treated and aged specimen, the intragranular α phase does not undergo variant selection, instead, self-accommodation occurs among α variants, leading to a cross distribution of α phase variants at 60°. The variant selection of the film-like grain boundary α phase is influenced by the misorientation of adjacent β grains. A minor misorientation causes α phase to retain a Burgers orientation relationship with β grains on either side, whereas a major misorientation affects the precipitation of the α phase due to the interface orientation. The variant selection of the grain boundary Widmanstätten microstructure relies on the nucleation site. When the nucleation takes place at the film-like grain boundary α phase, it selects the same variants as the film-like grain boundary α phase. Nonetheless, when the nucleation occurs at the interface between the film-like grain boundary α phase and the β matrix, it is influenced by both. Reference | Related Articles | Metrics

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  Effect of Zn/Mg ratio on microstructure, mechanical properties and corrosion resistance of 7075 aluminum alloy He Zongzheng, Wu Mingdong, Yuan Shuo, Yao Shuwei, Xiao Daihong, Huang Lanping, Liu Wensheng Heat Treatment of Metals    2024, 49 (5): 1-9.   doi:10.13251/j.issn.0254-6051.2024.05.001 Abstract （185）      PDF （9223KB）（127）       Knowledge map    Effect of Zn/Mg ratio (mass fraction) on microstructure, mechanical properties, and corrosion resistance of 7075 aluminum alloys was investigated by means of optical microscope, scanning electron microscope, transmission electron microscope, tensile test, microhardness test and corrosion test. The results show that with the increase of Zn/Mg ratio from 1.76 to 2.90, the grain size of the as-cast alloy increases, the T6 age-hardening rate of the alloy is accelerated, and the time to reach peak hardness is shortened. The increase in Zn/Mg ratio results in a decrease in the recrystallization rate of the T6 peak-aged alloy and an increase in the percentage of the low-angle grain boundaries. The tensile strength of the alloy under the T6 peak-aging treatment with the Zn/Mg ratio of 2.10 is 634 MPa, the yield strength of the alloy is 588 MPa, and elongation is 8.4%. The tensile strength of the T74 aged alloy is 613 MPa, yield strength is 542 MPa, and elongation is 8.9%, and alloys with Zn/Mg ratio of 2.10 in both aging states exhibit good strength while maintaining high elongation. The corrosion resistance of the aged alloy decreases as the Zn/Mg ratio increases from 1.76 to 2.90. The corrosion resistance of the alloy after T74 aging treatment is better than that of the alloy under the T6 peak-aging state. Reference | Related Articles | Metrics

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  Numerical simulation of vacuum isothermal quenching process of H11 steel large module for die-casting dies Tu Yujie, Li Bingchen, Chen Hao, Wu Xiaochun Heat Treatment of Metals    2024, 49 (7): 1-8.   doi:10.13251/j.issn.0254-6051.2024.07.001 Abstract （102）      PDF （5794KB）（126）       Knowledge map    Based on the metal-thermo-mechanical coupled theory, multi-field coupled numerical models of the H11 steel large module (500 mm×500 mm×500 mm) during vacuum isothermal quenching was established, and the numerical simulation of different vacuum isothermal quenching processes was carried out to study the evolution of the temperature field, structure field and stress field. The results show that compared with direct quenching, isothermal quenching can effectively reduce the temperature difference and the stress between the core and surface during the cooling process of the module to avoid the risk of distortion and cracking. Vacuum isothermal quenching can increase the volume fraction of bainite in the core of the module while avoiding pearlite formation and carbides precipitating along the grain boundary, and with the increase of the isothermal time, the more core bainite will be generated. The experimental verification of vacuum isothermal quenching at 500 ℃ for 1 h carried out by using industrial equipment indicates that the temperature curves at different positions of the module are in good agreement with the simulation results, and the type of bainite formed in the core of the module after vacuum isothermal quenching is lower bainite with good toughness. Reference | Related Articles | Metrics

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  Heat treatment for toughening technology of cold working die steel SKD11 Yuan Zhizhong, Wang Mengfei, Zhang Bocheng, Duan Xubin, Li Biaomin, Yang Haifeng, Luo Rui, Cheng Xiaonong Heat Treatment of Metals    2023, 48 (9): 1-7.   doi:10.13251/j.issn.0254-6051.2023.09.001 Abstract （235）      PDF （5140KB）（289）       Knowledge map    SKD11 steel plate after hot rolling and spheroidizing annealing was used. Two kinds of complex phase heat treatment processes, A-Q-A (Austempering-Quenching-Austempering) and Q-T-A (Quenching-Tempering-Austempering), as well asconventional Q-T(Quenching-Tempering) heat treatment process were carried out.The effect of heat treatment process on the microstructure, hardness and impact absorbed energy was studied. The results show that the microstructure of the specimens after A-Q-A and Q-T-A is the combination of lower bainite (LB) and martensite (M). The content of retained austenite is 13.2% and 18.6% for A-Q-A and Q-T-A, respectively. After A-Q-A, Q-T-A and conventional heat treatment Q-T, the hardness of the specimens is 58.5, 58.6 and 60.5 HRC and the impact absorbed energy is 31.3, 27.6 and 15 J, respectively. The excellent combination of strength and toughness of the SKD11 steel plate is realized by the duplex-phase heat treatments, which does a beneficial exploration in improving the toughness of the cold working die steel. Reference | Related Articles | Metrics

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  Strength evolution law of electric heat treated commercially pure Al wire Zhang Yi, Hou Jiapeng, Yuan Qulong, Zhang Zhenjun, Chen Ling, Zhang Zhefeng Heat Treatment of Metals    2023, 48 (5): 49-53.   doi:10.13251/j.issn.0254-6051.2023.05.008 Abstract （53）      PDF （3454KB）（169）       Knowledge map    Traditionally annealing and electric heat treatment of commercially pure Al wire were carried out by using drying oven and current-providing device, respectively. The influence law and mechanism of traditionally annealing and electrical heat treatment at different temperatures on strength and microstructure of the commercially pure Al wire were investigated. The results show that when the heat treatment temperature is the same, the tensile strength and the grain size of the electric heated commercially pure Al wire is respectively lower and larger than those of the traditionally annealed, the main mechanism of which is the overheating caused by local Joule heating effect on grain boundaries in the commercially pure Al wire. Reference | Related Articles | Metrics

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  Laser quenching process optimization and microstructure and properties of H13 steel Ma Xin, Shi Qiang, Chen Yanzhong, Li Qiang, Zhang Yueting, Zhao Long Heat Treatment of Metals    2023, 48 (7): 266-270.   doi:10.13251/j.issn.0254-6051.2023.07.044 Abstract （68）      PDF （2574KB）（160）       Knowledge map    Surface of H13 steel was strengthened by laser quenching, and the quenching process was optimized by range analysis of orthogonal test. The microhardness and friction and wear properties of the specimen under the optimum process parameters were studied, and the phase composition and microstructure of the laser quenching surface were analyzed. The results show that the optimum laser quenching process parameters are laser power of 600 W, scanning speed of 6 mm/s and lapping rate of 20%. Under this optimum process, the average hardness of hardened layer of the H13 steel is 774 HV0.1, which is about 3 times than that of the matrix, the depth of the hardened layer is 0.87 mm, and the friction coefficient and wear amount are about 0.367 and 0.0015 g, which are 50% and 60.5% lower than those of the matrix, respectively. The hardened layer is mainly composed of lath and acicular mixed martensite, retained austenite and a small amount of cementite. Reference | Related Articles | Metrics

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  Effect of chemical composition on heat treatment properties of X32 steel for bimetal saw blade Zeng Bin, Wang Jing, Liang Liang, Chen Gang, Su Bin Heat Treatment of Metals    2023, 48 (5): 83-89.   doi:10.13251/j.issn.0254-6051.2023.05.014 Abstract （86）      PDF （4321KB）（189）       Knowledge map    Two X32 steels with different contents of C and N were prepared in order to develop novel X32 steel material with lower alloy content and more economical production cost. The feasibility was discussed through the characterization of properties and microstructure. The static CCT curves of two X32 steels were presented, and microstructure and mechanical properties of the hot rolled intermediate billet of these two steels after heat treatment were studied. The heat treatment experimental result was verified by industrial trial production of the two X32 steel cold strips. The research shows that X32 steel can achieve obvious microstructure refinement, strength and hardness improvement by increasing C and N content by adopting V-C and V-N microalloying technology. Therefore, without affecting quality, it is feasible to reduce the content of Ni, Cr and Mo alloy but increasing the content of C and N by using V-C and V-N microalloying technology, which points out the direction for developing new X32 steel with more economic production cost. Reference | Related Articles | Metrics

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  Effect of Cu on mechanical properties of 390 MPa grade CrNiMo series low-alloy ship steel plates Li Weixian, Peng Wei, Hu Jie, Liu Tengshi, Zhou Luhai, Dong Han Heat Treatment of Metals    2024, 49 (4): 1-7.   doi:10.13251/j.issn.0254-6051.2024.04.001 Abstract （117）      PDF （5141KB）（114）       Knowledge map    CrNiMo low-alloy marine steels without Cu(961-Base) and with 1wt% Cu(961-Cu) quenched twice and then tempered at high temperature were prepared, and then the effect of Cu on microstructure, mechanical properties, precipitated phase and texture characteristics of the steel was investigated by thermal dilatometer, optical microscope(OM), scanning electron microscope(SEM), electron backscatter diffractometer(EBSD) and transmission electron microscope(TEM). The results show that the Ac1 and Ac3 temperatures of the 961-Base steel are 767 ℃ and 905 ℃, and that of 961-Cu steel are 762 ℃ and 895 ℃, respectively. The ferrite/bainite transformation temperatures of the 961-Cu steel are lower than that of the 961-Base steel. The microstructure of the tested steels after heat treatment is dominated by lath bainite(LB) and a small amount of quasi-polygonal ferrite(QPF). The lath of the 961-Cu steel is more refined, which increases the proportion of large-angle grain boundaries by 6.8% and is more beneficial to hinder crack propagation. Compared with that of the 961-Base steel, the yield strength and tensile strength of the 961-Cu steel are increased by 84 MPa and 68 MPa, respectively, and the low-temperature impact absorbed energy are increased from 220 J to 267 J. The impact fracture of the tested steels is dominated by the shear lip and fiber zone, with the 961-Cu steel having a greater shear section ratio. The Cu-rich phase (fcc structure) is non-uniformly precipitated in the matrix and on dislocation line in the form of globular or rods, producing a precipitation strengthening effect. Both the tested steels are characterized by α and γ textures, with the 961-Cu steel containing a higher proportion of γ textures that is conducive to deformation. Reference | Related Articles | Metrics

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  Status of quenching technology and the standard research Hu Xiaoli1, Li Qiao1, ZuoXunwei2, ChenNailu2 HTM    doi:10.13251/j.issn.0254-6051.2017.02.023

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  Microstructure, properties and dynamic recrystallization behavior of 20Mn23AlV non-magnetic structural steel hot rolled plate Luo Xiaoyang, Cheng Ganghu, Jin Ke, Zhou Weilian, Hou Yuanyuan, Tang Xingchang Heat Treatment of Metals    2024, 49 (7): 91-99.   doi:10.13251/j.issn.0254-6051.2024.07.014 Abstract （35）      PDF （4985KB）（108）       Knowledge map    Experimental study on the density, microstructure, and mechanical properties of 20Mn23AlV non-magnetic structural steel hot-rolled plate was conducted. Additionally, multi-pass thermal simulation tests were performed to investigate the changes in microstructure and magnetic properties before and after the tests. The results show that, due to the addition of the Al element, the density of the tested steel is reduced by approximately 0.192 g/cm3 compared to that of common steels. The average tensile strength of the hot-rolled plate of non-magnetic steel is 721 MPa, the yield strength is 371 MPa, and the elongation after fracture is 69.5%, indicating good strength-ductility matching. It is found that through multi-pass thermal simulation experiments with 60% hot compression deformation, the tested steel undergoes dynamic recrystallization behavior at 950 ℃, with the average austenite grain size decreasing from 10.24 μm to 6.08 μm. There is no phase transformation before and after the multi-pass thermal simulation tests, and the relative permeability measured is 1.001 and 1.002, respectively, which meets the requirements for the magnetic properties of non-magnetic steel. Reference | Related Articles | Metrics

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  Effect of deformation heat treatment on microstructure and properties of Ti45Zr20Nb15V(10-x)Al10Mox refractory high entropy alloy Li Zhenglong, Pang Jingyu, Tang Guangquan, Cheng Lufan, Zhang Caiwei, Hou Xingyu, Li Wen, Zhang Haifeng Heat Treatment of Metals    2024, 49 (7): 47-53.   doi:10.13251/j.issn.0254-6051.2024.07.008 Abstract （62）      PDF （5038KB）（106）       Knowledge map    Ti45Zr20Nb15V(10-x)Al10Mox (x=0, 0.5, 1.0) refractory high entropy alloy was prepared by adding trace amounts of Mo element to the Ti45Zr20Nb15V10Al10 refractory high entropy alloy matrix, which strain hardening ability and plasticity were improved by deformation heat treatment. Microstructure and mechanical properties of the as-cast specimen and cold-rolled (deformation of 80%) and annealed (600 ℃×5 h and 800 ℃ for 1 h) specimen were investigated using X-ray diffractometer, field emission scanning electron microscope, and universal mechanical testing machine. The test results show that the as-cast alloy has a single-phase BCC structure, and the addition of Mo element increases the yield strength and maintains a fracture elongation of about 10%. After cold rolling and annealing, the microstructure of the alloy becomes BCC+Al3Zr4 dual phase with a large amount of approximately spherical nanoscale Al3Zr4 particles precipitated at and near grain boundaries, causing the alloy to transition from strain softening to strain hardening, and the yield strength of the alloy is maintained at 1100 MPa, while the fracture elongation is significantly improved. When the Mo content is 0.5%, the fracture elongation of the alloy after cold rolling annealing increases from 9.9% in as-cast state to 16.9%, exhibiting excellent strength plasticity matching and a density of only 5.638 g/cm3. Reference | Related Articles | Metrics

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  Friction and wear performance of sulfurized layer on gray cast iron Li Yelin, Jia Bo, Shi Zhengliang, Hu Wenxiang, Guan Yunqi, Zheng Huiyun Heat Treatment of Metals    2023, 48 (10): 266-273.   doi:10.13251/j.issn.0254-6051.2023.10.041 Abstract （47）      PDF （3505KB）（139）       Knowledge map    Solid lubricating layers of sulfurized layer and phosphate layer were prepared on the surface of gray cast iron by low temperature ion sulfurization technology and chemical conversion technology, respectively. SEM-EDS, XRD, nano-indentation apparatus and X-ray stress analyzer were used to analyze the component elements, microstructure, thickness, hardness, residual stress and wear scar morphologies of the solid lubricating layers. The anti-friction and wear properties of the gray cast iron substrate and surface solid lubrication layer were studied by friction and wear test. The wear volume after friction and wear test was analyzed by using three-dimensional white light interferometer. The results show that both the phosphate layer and the porous structure of the sulfurized layer on the surface of gray cast iron have the characteristics of oil storage lubrication, while the surface hardness and residual stress of the sulfurized layer are higher than that of the phosphate layer. The sulfurized layer is detected to be a covalent bond compound FeS with antifriction and lubrication effect, which is formed when the active sulfur atoms infiltrate into the matrix, there is also a dynamic equilibrium process of active sulfur atoms transfer and recombination during the grinding process of gray cast iron substrate and sulfurized layer. Therefore, compared with the phosphate layer under the same friction conditions, the friction coefficient of the sulfurized layer is reduced by 23.5% and the wear rate is decreased by 31.6%, i.e., the anti-friction, wear-resisting and wear-resisting properties of sulfurized layer is better than that of phosphate layer, the COP of compressor parts after sulfurizing treatment is significantly improved. Reference | Related Articles | Metrics