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  Tempering brittleness of 2Cr13 stainless steel Zhu Hongwei, Wang Ping, Hu Wanting, Chen Xin, Huang Yanjun, Yu Ruixing, Zhuang Yuanhong, Chen Yongshuan Heat Treatment of Metals    2022, 47 (12): 234-236.   doi:10.13251/j.issn.0254-6051.2022.12.039 Abstract （215）      PDF （642KB）（28）       Knowledge map    Changes of hardness, impact property and fracture morphology evolution of the 2Cr13 stainless steel after tempering near the tempering brittle temperature interval were studied. The results show that hardness of the 2Cr13 stainless steel after tempering at 490-550 ℃ is 40-50 HRC, the corresponding impact property shows a downward trend; After tempering at 570-620 ℃, the hardness of the 2Cr13 stainless steel is 30-38 HRC, the impact property gradually increases. Through the observation of the impact fracture morphology, after tempering at 490-560 ℃, the fracture mode first changes from cleavage fracture to intergranular fracture. With the increase of the tempering temperature, it eventually changes to a fracture mode along the grain+cleavage. Microscopically, the size of the fracture surface along the grain gradually decreases, and the number of cleavage gradually increases, which is manifested by the improvement of the impact performance on the macroscopic level. Reference | Related Articles | Metrics

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  Effect of vacuum low pressure carburizing on microstructure and properties of austenitic stainless steels 304 and 316L Cheng Ru, Tian Yong, Song Chaowei, Wang Haojie Heat Treatment of Metals    2022, 47 (9): 1-5.   doi:10.13251/j.issn.0254-6051.2022.09.001 Abstract （214）      PDF （660KB）（174）       Knowledge map    Surface strengthening of 304 and 316L austenitic stainless steels was processed by using vacuum low pressure carburizing process. The microstructure, phase composition and microhardness distribution of the carburized layers were analyzed by means of optical microscope, scanning electron microscope, Thermo-Calc software, X-ray diffractometer and microhardness tester. The offsets of different diffraction peaks in the carburized layers and the changes in lattice parameters before and after carburizing of the tested steels were calculated. Combined with the effects of molybdenum on carburizing process of the austenitic stainless steels, the differences in the carburized layer thickness, surface hardness and mechanism of carbides precipitation after carburizing of 304 and 316L austenitic stainless steels were compared and studied. The results show that the carburized layers produced by 750 ℃ carburizing for 2.6 h are composed of expanded austenite and Cr23C6 phases, the austenite lattice constant has increased by 1.33% and 1.14% respectively for 304 and 316L stainless steels, and Cr23C6 is mainly precipitated in strip shape on the expanded austenite grain boundaries. The surface hardness of the 304 and 316L stainless steels after carburizing at 750 ℃ for 2.6 h is over 2 times higher than that of substrate. Reference | Related Articles | Metrics

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  Effect of solution treatment on microstructure of carbide in K447A superalloy Wu Wenjin, Li Xianghui, Li Xuechen, Chen Jingyang, Tang Xin Heat Treatment of Metals    2022, 47 (6): 89-92.   doi:10.13251/j.issn.0254-6051.2022.06.016 Abstract （183）      PDF （2512KB）（19）       Knowledge map    Microstructure and precipitation behavior of carbides in K447A alloy under different solution treatments were analyzed by scanning electron microscopy(SEM). The results show that primary carbides in the as-cast K447A alloy are of the MC type, in the form of blocks, skeletons and Chinese characters, and are distributed between dendrites and grain boundaries. After heat treatment, primary MC carbides are broken, and a layer of γ' phase coating layer is formed on the surface. During heat treatment, the composition of the primary MC carbides changes, and the primary carbides such as TaC, TiC, and WC are decomposed, and HfC is least affected. After heat treatment, a large number of fine and dispersed granular secondary MC carbides dominated by HfC precipitate in the interdendritic and residual eutectic regions near the primary MC carbides. When solution-treated at 1185 ℃ for 2 h and aged at 870 ℃ for 20 h, the amount of secondary MC precipitation is the largest. Reference | Related Articles | Metrics

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  Effect of solution temperature on mechanical properties and corrosion resistance of super duplex stainless steel 2507 Gu Guochao, Li Ruifen, Xin Zhenmin, Xiang Lixin, Xu Wenhua, Lü Yupeng Heat Treatment of Metals    2022, 47 (6): 1-6.   doi:10.13251/j.issn.0254-6051.2022.06.001 Abstract （172）      PDF （3745KB）（321）       Knowledge map    Effect of solution temperature on microstructure, mechanical properties and corrosion resistance of 2507 super duplex stainless steel was investigated by using optical microscope, scanning electron microscopy, XRD, tensile test and electrochemical analysis. The thermodynamic equilibrium phase diagram of the 2507 duplex stainless steel was calculated by Thermo-Calc thermodynamic software and compared with the test results. The results show that σ phase can be eliminated by solution treatment at temperatures higher than 1050 ℃. With the increase of solution temperature, the content of ferrite phase increases, the content of austenite phase decreases, and the volume fraction ratio of α/γ increases. The duplex stainless steel has better comprehensive mechanical properties after solution treatment at 1050-1100 ℃ for 30 min and water cooling, of which the yield strength, tensile strength and elongation are more than 600 MPa, 840 MPa and 35%, respectively. The duplex stainless steel can obtain better corrosion resistance after solution treatment at 1050 ℃ for 30 min. Reference | Related Articles | Metrics

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  Microstructure and wear resistance of AlCoCrFeMnZr near-eutectic high-entropy alloy Wang Zhixin, Yang Cheng, Ma Mingxing, Wang Bozhen, Dong Chen, Li Shangzhi, Hou Runsen Heat Treatment of Metals    2023, 48 (1): 1-5.   doi:10.13251/j.issn.0254-6051.2023.01.001 Abstract （169）      PDF （695KB）（145）       Knowledge map    AlCoCrFeMnZr near-eutectic high-entropy alloy was prepared by vacuum melting, then its crystal structure, morphology, hardness and wear resistance were tested by means of XRD, SEM, microhardness tester and friction and wear testing machine. The results show that the phase structure of the AlCoCrFeMnZr alloy is BCC+HCP dual-phase structure, composing of primary phase and fine lamellar eutectic. The primary phase consists of the HCP phase enriched in Cr, Fe, and Zr, which grows in a dendritic manner. The main elements in the dendrite region (α phase) of the lamellar eutectic structure are Co, Cr and Fe, and the main elements in the intergranular (β phase) are Al and Zr, which conforms to the structure and element distribution of high-entropy alloys. The wear model changes from adhesive wear and abrasive wear to oxidative wear, and the friction factor shows a trend of increasing first and then decreasing, and the average friction factor is 0.5432, the microhardness is 768.8 HV0.5, that means the alloy has excellent hardness and wear resistance. Reference | Related Articles | Metrics

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  Effect of solution treatment and aging on microstructure and hardness of TC11 titanium alloy Zhu Ningyuan, Chen Shihao, Liao Qiang, Chen Qiuming, Lai Wenkun, Zuo Shoubin Heat Treatment of Metals    2022, 47 (12): 62-66.   doi:10.13251/j.issn.0254-6051.2022.12.010 Abstract （162）      PDF （582KB）（45）       Knowledge map    Effects of solution temperature and solution time on microstructure and microhardness of TC11 titanium alloy bar under the same aging treatment processes were studied. The results show that when the TC11 titanium alloy is solution treated below the phase transition point, the content of equiaxed primary α phase increases with the increase of solution temperature. When the solution temperature approaches the phase transition point, the content of equiaxed primary α phase decreases rapidly. When the solution temperature is 950 ℃, with the increase of solution time, the grain boundary α phase begins to grow, and the lamellar α phase turns into the mixed microstructure of bulk α phase and equiaxed α phase. When the solution time is fixed, the hardness of the TC11 titanium alloy decreases first and then tends to be stable with the increase of solution temperature. The hardness reaches the maximum value when solution temperature is 950 ℃ and solution time is 120 min. Reference | Related Articles | Metrics

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  Effect of solution treatment temperature and time on corrosion resistance of high nitrogen stainless steel Zhang Cunshuai, Liu Jimeng, Li Hao, Zhao Dingguo, Wang Shuhuan, Ni Guolong Heat Treatment of Metals    2022, 47 (8): 141-147.   doi:10.13251/j.issn.0254-6051.2022.08.023 Abstract （149）      PDF （593KB）（46）       Knowledge map    High nitrogen nickel-free austenitic stainless steel with 0.54%N was prepared by vacuum induction furnace+electroslag remelting furnace under 0.08 MPa. After hot rolling, the tested steel was solution treated at 800, 900, 1000, 1100 and 1200 ℃ for different time, respectively. The microstructure and corrosion resistance of the tested steel were studied with different solution treatment processes, in which the corrosion resistance was studied in 3.5% NaCl solution by potentiodynamic polarization curve, and the mass loss ratio and corrosion rate were calculated after soaking in 6% FeCl3 solution for 8 days. The results show that solution treatment has a great influence on microstructure and corrosion resistance of the high nitrogen stainless steel. The tested steel after solution treatment at 1000 ℃ and 1100 ℃ has a single austenite structure. The precipitation phase Cr2N exists in the microstructure of the tested steel without heat treatment and in that solution treated at 800 ℃ and 900 ℃. In the tested steel solution treated at 1200 ℃, the ferrite structure is precipitated from the austenite. The tested steel heated at 1100 ℃ for 1 h has the best corrosion resistance, and the corrosion rate is only 1.35×10-5 g·cm-2·h-1. While the corrosion resistance of the tested steel heated at 800 ℃ for 3 h is the worst, the corrosion rate is as high as 8.18×10-4 g·cm-2·h-1. The corrosion resistance of 316L stainless steel is somewhere in between, and the corrosion rate is 1.24×10-4 g·cm-2·h-1. 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 （142）      PDF （5140KB）（178）       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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  Effects of solution and aging treatments on mechanical properties and microstructure of Al-Cu-Mn-Er cast alloy Wu Yang, Huang Hui, Shi Wei, Wen Shengping, Wu Xiaolan, Rong Li, Wei Wu Heat Treatment of Metals    2022, 47 (6): 7-12.   doi:10.13251/j.issn.0254-6051.2022.06.002 Abstract （137）      PDF （4148KB）（167）       Knowledge map    Effects of different solution and aging treatments on microstructure and mechanical properties of Al-Cu-Mn-Er alloy were studied by optical microscope, scanning electron microscope, XRD, DSC test, hardness test and tensile test. The results show that the optimal process of solution and aging treatments of the as-cast alloy is solution treating at 540 ℃ for 12 h and aging at 185 ℃ for 6 h, under which there is no overheating or "overburning" phenomena, the solute atoms are fully diffused, and a large amount of residual phases generated during the casting process are redissolved into the matrix. Meanwhile, the alloy has the highest hardness value of 142.28 HV0.1, tensile strength of 370.37 MPa, yield strength of 300.34 MPa, and elongation of 6.50%. Reference | Related Articles | Metrics

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  “Thought” of metallic materials Yuan Zhizhong, Dai Qixun, Wang Andong, Ju Yulin, Cao Fuyang, Luo Rui Heat Treatment of Metals    2023, 48 (5): 1-5.   doi:10.13251/j.issn.0254-6051.2023.05.001 Abstract （131）      PDF （1390KB）（103）       Knowledge map    “Thought” of metallic materials is refined from the systematic and comprehensive perspectives. The contradictory law of the evolution process of metallic materials properties is revealed. The complexity of the role of alloy elements is summarized. The quantitative and qualitative change law of microstructure evolution of metallic materials is expounded, and the multidirectional variability of heat treatment processes is illustrated as well. Reference | Related Articles | Metrics

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  Effect of tempering temperature and phosphating on mechanical properties and microstructure of 40CrNiMoA steel Li Shijian, Pan Xin, Liu Yanmei, Yang Lixin, Hu Fuchang Heat Treatment of Metals    2022, 47 (12): 99-102.   doi:10.13251/j.issn.0254-6051.2022.12.017 Abstract （123）      PDF （584KB）（30）       Knowledge map    Aiming at the problem of unqualified shear property of standard parts which were made of 40CrNiMoA steel, the effect of tempering temperature on mechanical properties and microstructure was studied, and then the effects with and without phosphating process on shear property were compared and analyzed. The results show that with the increase of tempering temperature, both the tensile strength and shear property decrease gradually, while the plasticity is almost unchanged. The shear property of the steel with phosphating process is lower than that without. Thus, it is proposed that in order to ensure shear property of the product, the lower tempering temperature should be selected, and the effect of phosphating on reducing shear property should be simultaneously considered. Reference | Related Articles | Metrics

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  Comparative analysis on properties of 8Cr4Mo4V steel for bearing after vacuum gas quenching and isothermal salt bath quenching Tong Rui, Yu Xingfu, Liu Yongbao, Xia Yunzhi, Su Yong, Jin Yingli Heat Treatment of Metals    2022, 47 (7): 9-14.   doi:10.13251/j.issn.0254-6051.2022.07.002 Abstract （121）      PDF （600KB）（54）       Knowledge map    Properties of 8Cr4Mo4V steel for bearing after vacuum gas quenching and isothermal salt bath quenching were comparatively analyzed by microstructure observation and property test. The results show that the martensite in the 8Cr4Mo4V steel is obtained after vacuum quenching, while the mixed microstructure of martensite and bainite is obtained after isothermal salt bath quenching. There is carbide precipitation at the grain boundary of vacuum quenched steel, and the grain boundary characteristics are obviously shown after chemical etching. However, the amount of carbide precipitation at the grain boundary of isothermal salt bath quenched steel is less, and the grain boundary characteristics of the steel are not obvious. Then after tempering treatment, a large number of carbides precipitate in the steels, and that in the steel isothermal salt bath quenched are larger in size and quantity than that of vacuum quenched. The test results of hardness and wear resistance show that the hardness of the isothermal salt bath quenched steel is 61.78 HRC, higher by 1.5 HRC than that of the vacuum quenched steel (60.28 HRC). The friction and wear resistance of the isothermal salt bath quenched steel is higher than that of the vacuum quenched. Compared with that of vacuum quenching, the mechanical properties of the steel after isothermal salt bath quenching are better: the tensile strength is higher by 164 MPa and 50 MPa respectively at room temperature and at high temperature, the impact absorbed energy is increased by 46.9%, and the rotary bending fatigue strength is increased by 22%, from 860 MPa to 1050 MPa. Reference | Related Articles | Metrics

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  Effect of thermal deformation on bainite transformation of plastic mould steel SDFT600 Zhang Zheng, Chen Jinlei, Zhang Min, Qiao Junwei Heat Treatment of Metals    2022, 47 (8): 1-6.   doi:10.13251/j.issn.0254-6051.2022.08.001 Abstract （120）      PDF （608KB）（78）       Knowledge map    Effect of thermal deformation on bainite transformation of plastic mould steel SDFT600 during continuous cooling was analyzed by means of thermal simulation machine, thermal dilatometer, scanning electron microscope, etc. The results show that with the parameters suitable for forging production of large plastic mould steel blocks, thermal deformation promotes bainite transformation. At same continuous cooling rate, the bainite transformation start temperature of dynamic CCT specimen is higher than that of static CCT specimen, at cooling rate of 0.5 ℃/s, the temperature difference reaches 96 ℃. Thermal deformation reduces the stability of retained austenite, and at cooling rate of 0.5 ℃/s, the bainite content of dynamic CCT specimen is higher than that of static CCT specimen. When the continuous cooling rate is less than 0.1 ℃/s, the content of retained austenite of dynamic CCT specimen is lower than that of static CCT specimen. Hardness uniformity under thermal deformation condition is better, which is beneficial to the final quality of mould blocks. Reference | Related Articles | Metrics

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  Heat treatment and space environment performance of high strength aluminum alloy parts by selective laser melting Jiang Chao, Jia Dongyong, Zhou Zhiyong, Tian Zheng, Guo Xingye, Wang Zhe, Han Xiuzhu Heat Treatment of Metals    2022, 47 (7): 1-8.   doi:10.13251/j.issn.0254-6051.2022.07.001 Abstract （119）      PDF （678KB）（94）       Knowledge map    High-strength aluminum alloy specimens of aluminum-magnesium-scandium-zirconium system were prepared by adopting the additive manufacturing technologys of selective laser melting (SLM). The evolution of the microstructure and mechanical properties of the specimens during annealing and solution aging treatment were studied. In addition, high and low temperature cycle experiments were carried out on the specimens to simulate the temperature change of the space environment, and then the evolution of mechanical properties after high and low temperature cycles were studied. The results show that for the high-strength aluminum alloy prepared by the SLM, the annealing treatment can significantly improve its mechanical properties. After the high and low temperature cycle experiment simulating the space environment, mechanical properties of the specimens remain unchanged, so it meets the performance requirements under the space alternating temperature. Reference | Related Articles | Metrics

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  Quenching crack analysis and heat treatment process optimization of 2Cr13 steel special-shaped die forging parts Wang Gaoyuan, Wang Kai, Zhang Zhimei Heat Treatment of Metals    2022, 47 (11): 45-53.   doi:10.13251/j.issn.0254-6051.2022.11.007 Abstract （118）      PDF （567KB）（22）       Knowledge map    In order to solve the batch surface cracking problem of a 2Cr13 steel special-shaped die forging part after quenching and tempering by analyzing the reasons of cracking from reviewing production process, simulating surface stress change during quenching process and observing the microstructure of the parts and the crack morphology. Meanwhile the influence of quenching method on surface structure and mechanical properties of workpiece was verified by heat treatment tests. The results show that the cracking of 2Cr13 steel special-shaped die forging parts after quenching is related to the shape of the forging part, quenching heating method and quenching temperature. The risk of quenching cracking can be reduced by increasing the excess allowance of forging parts, or applying hot charging and lower quenching heating temperature. Quenching at 1000 ℃ via hot charging is adopted as the optimized heat treatment method of products. Reference | Related Articles | Metrics

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  Effect of mechanical alloying time on microstructure and corrosion resistance of laser clad coating of Ni6Cr4W1.5Fe9Ti high-entropy alloy Sun Defu, Sun Zhicheng, Gu Zhen, Xi Shengqi, Sun Chongfeng, Li Shiliang, Su Chengming, Wang Chunchang Heat Treatment of Metals    2023, 48 (3): 1-7.   doi:10.13251/j.issn.0254-6051.2023.03.001 Abstract （118）      PDF （4952KB）（116）       Knowledge map    Clad coating of mechanical alloyed Ni6Cr4W1.5Fe9Ti high-entropy alloy powder was prepared by laser melting deposition. The effect of mechanical alloying time on microstructure and corrosion resistance of the coating was studied. The results show that the increase of mechanical alloying time can promote the homogenization of alloy powder composition, the densification of coating and the grain refinement of microstructure. After mechanical alloying rod grinding for 4 h, the components of high-entropy alloy powder are evenly distributed, and the FCC+BCC two-phase solid solution structure is formed. After laser melting deposition, the structure of two-phase solid solution is transformed into FCC single-phase solid solution, which is mainly composed of 4-6 μm equiaxed crystals and a small amount of cellular crystals. Among them, the coating prepared by powder mechanical alloying rod grinding for 4 h has the highest density, hardness and the best corrosion resistance, and its corrosion resistance is nearly two orders of magnitude higher than that of the coating prepared by powder mechanical alloying rod grinding for 0 h. Reference | Related Articles | Metrics

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  CCT curves and impact property of Q355D hot rolled H-steel Wang Wenzheng, Ma Yongfu, Ma Jinhong, Zhang Guiying, Tian Yaqiang, Cheng Xinchao, Li Hongbin, Chen Liansheng Heat Treatment of Metals    2023, 48 (1): 127-132.   doi:10.13251/j.issn.0254-6051.2023.01.022 Abstract （114）      PDF （574KB）（31）       Knowledge map    Continuous cooling transformation rule of Q355D hot-rolled H-steel was investigated on Glebble-3500 thermal simulation test machine by means of expansion method and metallography hardness method. In addition, static CCT curves were obtained. The results show that from the CCT curves, the microstructure of the steel is composed of ferrite and pearlite when the cooling rate is less than 1 ℃/s, ferrite, pearlite and bainite when the cooling rate is 1-10 ℃/s, and ferrite, bainite and martensite when the cooling rate is 20-50 ℃/s. With the increase of cooling rate, the hardness of the Q355D hot-rolled H-steel increases, and the hardness increases from 171 HV0.2 to 301 HV0.2. According to CCT curves, different rolling experiment schemes are worked out. When the total reduction is 75%, the strain rate is 0.3 s-1 and the deformation temperature is 1150 ℃, the ferrite grain size of the tested steel is 8.13 μm, and the impact absorbed energy at -20 ℃ is 146 J, with the best performance. Reference | Related Articles | Metrics

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  Formation causes of white bright layer on surface of vacuum oil quenched martensitic stainless steel Ding Yahong, Zhu Kai, He Jun, Zhu Ling, Wang Qiaoli, Li Jianfei Heat Treatment of Metals    2022, 47 (10): 275-282.   doi:10.13251/j.issn.0254-6051.2022.10.047 Abstract （109）      PDF （652KB）（36）       Knowledge map    Surface of martensitic stainless steel nut was prone to brown yellow rust in the air environment. The surface rust of martensitic stainless steel was analyzed by means of optical microscope, scanning electron microscopy and chemical element detection. The results show that a uniform white bright layer structure is formed on surface of the martensitic stainless steel after vacuum quenched in oil. The corrosion resistance of the white bright layer is worse than that of normal martensite. The white bright layer is easy to rust in the air, and the rust does not penetrate the white bright layer. Through the measurement of carbon content and mechanism analysis, it is considered that the necessary conditions for the formation of white bright layer are vacuum heating and oil cooling. Vacuum heating causes the depletion of alloy element Cr on the surface of stainless steel, and carbon infiltration due to the oil decomposition leads to the carburization of the surface, which leads to no martensitic transformation on the surface of stainless steel during quenching, forming a white bright layer structure with poor corrosion resistance. Reference | Related Articles | Metrics

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  Effect of tempering time on microstructure and properties of 1800 MPa hot stamping steel Song Ninghong, Lin Chao, Bi Wenzhen, Wang Wurong, Wei Xicheng Heat Treatment of Metals    2022, 47 (8): 112-117.   doi:10.13251/j.issn.0254-6051.2022.08.018 Abstract （109）      PDF （592KB）（30）       Knowledge map    Effect of tempering time (10-30 min) at 200 ℃ on microstructure and mechanical properties of a 1800 MPa hot stamping steel after flat forming at 930 ℃ for 4 min was studied by scanning electron microscope, electron backscattering diffraction and tensile test at room temperature. The results show that with the extension of tempering time, the tensile strength of the tested steel changes a little, while the yield strength and elongation after fracture both increase first and then decrease. The martensite sub-grain size is the smallest when tempered for 20 min, while the low angle grain boundary is the most when tempered for 10 min. After tempering at 200 ℃ for 10 min, the comprehensive mechanical properties of the hot stamping steel are the best due to the release of residual stress, the decrease of martensite sub-grain size and the increase of low angle grain boundary, of which the tensile strength is 1844 MPa, the elongation increases from 8.27% of quenched tested steel to 11.78%, and the product of strength and elongation reaches more than 21 GPa·%. It is concluded that short-time tempering is beneficial to the improvement of comprehensive properties of the tested ultra-high strength steel and the reliable application of hot stamping parts. Reference | Related Articles | Metrics

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  Effect of step quenching process on microstructure of high-Cr cast iron roll Zhang Bohan, Li Haonan, Gao Pengchong, Qiao Guiying, Liu Jiebing, Xiao Furen Heat Treatment of Metals    2022, 47 (7): 15-19.   doi:10.13251/j.issn.0254-6051.2022.07.003 Abstract （108）      PDF （600KB）（49）       Knowledge map    Step quenching process of high chromium cast iron roller was simulated by using LINSEIS L78 dilatometer. The effect of step quenching temperature on Ms point, microstructure and hardness was studied by means of thermal dilation, optical microscopy(OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the step quenching has little effect on the phase transformation during step quenching process, but it reduces the Ms point comparing with the direct quenching, and the Ms point decreases with the decrease of step quenching temperature. As the step quenching temperature is 560 ℃, the Ms point decreases a little, while the hardness increases to 62.1 HRC. Moreover, the hardness further increases to 64.5 HRC after tempering at 450-500 ℃. Reference | Related Articles | Metrics