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Effect of rare earth Y on microstructure and properties of H13 steel

Shu Ruixi, Yang Zhongmin, Cao Yanguang, Li Zhaodong, Chen Ying, Wang Huimin

Heat Treatment of Metals 2023, 48 (5): 70-77. doi:10.13251/j.issn.0254-6051.2023.05.012

Abstract （54）

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Effect of different rare earth Y contents on microstructure and properties of H13 die steel was studied. The laboratory used electroslag remelting to obtain H13 steel electroslag ingots with rare earth Y mass fractions of 0.0008%, 0.0060%, and 0.0120%, respectively. The effect of rare earth Y on microstructure was studied by means of OM, SEM, TEM and thermodynamic calculation. The effect of rare earth Y on properties was investigated by using impact testing machine and microhardness tester. The results show that the morphology of cryptocrystalline martensite in the H13 steel changes into dog-bone shape with the addition of rare earth Y. With the increase of Y content, the cryptocrystalline martensites show a local fine and dispersed distribution trend. The concentration of elements in the retained liquid phase in the H13 steel at the solidification end point reaches the concentration of high carbon and high alloy steel, resulting in the formation of liquidus carbide. When the content of rare earth Y is 0.0120%, the segregation degree of C element in the steel decreases from 1.292 to 0.529, the segregation degree of alloy elements Cr, Mo and V also decreases; the proportion of carbides with size larger than 5 μm in the steel is the lowest, and the average size of carbides is 3.13 μm; the transverse impact absorbed energy of the steel after heat treatment is 19.5 J, and the Vickers hardness after annealing and tempering are 244.4 and 525.5 HV0.5, respectively.

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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 （37）

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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.

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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 （31）

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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.

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Effects of Sn and cryogenic drawing on microstructure and properties of Cu-Cr-Zr alloys

Chen Jinshui, Wang Chong, Guo Chengjun, Peng Bingfeng, Zhang Jianbo, Xiao Xiangpeng, Yang Bin

Heat Treatment of Metals 2023, 48 (5): 90-97. doi:10.13251/j.issn.0254-6051.2023.05.015

Abstract （39）

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Cu-Cr-Zr-xSn alloys with different Sn contents were prepared by vacuum casting. Optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope(TEM) were used to analyze the microstructure evolution of the Cu-Cr-Zr-xSn alloys in the process of multi-stage thermo-mechanical treatment (rod blank→first drawing→950 ℃ solution treatment for 1 h→secondary drawing→peak aging at 450 ℃→room temperature drawing or cryogenic drawing→450 ℃ annealing), and the corresponding tensile strength and conductivity were measured. The effects of Sn element and cryogenic drawing on microstructure and properties of Cu-Cr-Zr alloy were mainly studied. The results show that both the Sn element and the cryogenic drawing can significantly improve the tensile strength of Cu-Cr-Zr alloy without causing too much loss of conductivity, where the Sn element will promote the formation of the Cr-rich primary phase. During the thermo-mechanical treatment process, the Cr-rich primary phase will be drawn into a fiber shape, which has the effect of fibre strengthening. Cryogenic drawing can improve the deformation resistance, resulting in a smaller deformed grain size, and also promote the Cr-rich primary phase to transform into a fibrous shape, which further improves the strength of the alloy.

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Effect of La on microstructure and properties of niobiumized layer on H13 steel

Tan Shenlu, Zhang Yue, Zhang Mengjiu, Xie Aijun, Shang Jian

Heat Treatment of Metals 2023, 48 (5): 98-103. doi:10.13251/j.issn.0254-6051.2023.05.016

Abstract （36）

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Effect of La content on microstructure and tribological properties of niobium carbide infiltration layer on H13 steel prepared by solid powder embedding method and niobiumizing agent with La addition was studied by means of optical microscope, scanning electron microscope, energy dispersive spectrometer and X-ray diffractometer. The results show that under different La content (0%-5%) conditions, the infiltration layer on the 3H13 steel is mainly composed of NbC. The addition of appropriate amount of La is beneficial for improving the density, hardness and tribological properties of the infiltration layer. With the increase of La content, the microhardness of the infiltration layer first increases and then decreases. When the La content is 3%, the microstructure of the infiltration layer is uniform and dense, with thickness of 7-9 μm and higher hardness (1669 HV0.2). Under corresponding friction conditions, as the La content increases, the average friction coefficient of the infiltration layer decreases first and then increases, and the wear resistance is the best when the rare earth La content is 3%.

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Effect of low Ti content (0-0.15%) on wear resistance of high strength steel

Lu Chunjie, Shao Chunjuan, Zhen Fan, Qu Jinbo

Heat Treatment of Metals 2023, 48 (5): 104-109. doi:10.13251/j.issn.0254-6051.2023.05.017

Abstract （38）

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Effect of low Ti content in range of 0-0.15% on wear resistance of a high strength tested steel was investigated by using a universal wear testing machine, and the microstructure, precipitate and wear morphology were analyzed. The results show that the precipitates in the tested steels are mainly TiC, with polygonal, oval, rectangular and circular shapes. The sizes of the precipitates can be classified into three levels based on their cross sectional area: large-sized (>100 μm²), micron-sized (1-100 μm²), and submicron-sized (<1 μm²). The micron-sized precipitates play a major role in improving wear resistance, while the effect of submicron-sized precipitates is less, and the large-sized precipitates have a negative effect. With the increase of Ti content, both the amounts of submicron- and micron-sized precipitates increase linearly, while the large-sized precipitates begin to appear when the Ti content is ≥0.10%. Accordingly, the highest wear resistance is obtained when the Ti content is 0.10%.

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Microstructure and properties of novel nitrogen-alloyed corrosion resistant plastic die steel Cr13

Zhang Hao, Chi Hongxiao, Wang Chengxi, Ma Dangshen, Fan Yi, Xie Guanli

Heat Treatment of Metals 2023, 48 (5): 110-115. doi:10.13251/j.issn.0254-6051.2023.05.018

Abstract （24）

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Microstructure and properties of novel N-alloyed and the traditional Cr13 corrosion resistant plastic die steels were investigated and compared by means of optical microscope, scanning electron microscope, hardness test, impact test and salt spray corrosion test. The results show that the novel N-alloyed Cr13 steel contains, except for the N, other alloying elements such as Ni, Mo and V. The difference in cleanliness between the novel N-alloyed Cr13 steel and traditional Cr13 steel is not significant, but the annealed novel N-alloyed Cr13 steel has a more uniform microstructure, lower hardness and thus the better cutting performance. Under the same heat treatment, the microstructure of the novel N-alloyed Cr13 corrosion resistant plastic die steel is more uniform, the amount of undissolved carbides reduces. The conventional Cr13 steel has a hardness of 52.7 HRC and an impact absorbed energy of 6.9 J, while the novel N-alloyed Cr13 steel has a comparable hardness with the value of 51.8 HRC but a much better toughness (12.3 J). After salt spray corrosion for 120 h, the novel N-alloyed Cr13 steel has fewer corrosion pits and the corrosion rate is 0.0594 g/(m²·h), while there are obvious corrosion pits on surface of the traditional Cr13 corrosion resistant plastic die steel and the corrosion rate is 0.1136 g/(m²·h), which means that the corrosion resistance of the novel N-alloyed Cr13 steel is better than that of the conventional Cr13 steel.

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Effect of rare earth on low temperature impact property of L360 pipeline steel

Wang Hongli, Feng Liang, Fan Xuanyu, Yu Yanchong

Heat Treatment of Metals 2023, 48 (5): 116-120. doi:10.13251/j.issn.0254-6051.2023.05.019

Abstract （33）

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L360RE pipeline steel was industrial produced, and the effect of trace rare earth elements on inclusion modification, hot rolled microstructure and low temperature impact property of the L360 pipeline steel was studied. The results show that adding 0.0062% rare earth, the content of O and S in the L360 pipeline steel is sharply reduced, the cleanliness of molten steel is significantly improved. The type of inclusions changes from MnS inclusions and Al₂O₃-CaO composite inclusions to RE₂O₂S rare earth inclusions, and the original large-size strip-shaped or irregular inclusions become small-size spherical inclusions, and the grain size decreases and the microstructure is refined, the transverse impact absorbed energy from room temperature to -60 ℃ is increased. At -60 ℃, the transverse impact absorbed energy of the L360RE pipeline steel is 19.2% higher than that of L360 pipeline steel.

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Diffusion mechanism and rules of nickel on surface of low carbon steel

Zhang Shixian, Xu Mingyue, Zhao Xiaoping, Li Yungang

Heat Treatment of Metals 2023, 48 (5): 121-128. doi:10.13251/j.issn.0254-6051.2023.05.020

Abstract （23）

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Nickel/low carbon steel surface composites were successfully prepared by means of aqueous solution electrodeposition+high temperature solid diffusion method. The diffusion mechanism of nickel on the surface of low carbon steel was studied. The diffusion rules of nickel on the surface of low carbon steel at different temperatures were obtained by using Den Broeder method. The results show that high temperature solid diffusion annealing realizes the metallurgical combination of nickel deposit layer and low carbon steel. Nickel atoms mainly diffuse along the grain boundary of low carbon steel, and its diffusion inhibits the growth of grains. Carbon, silicon, manganese, sulfur and phosphorus atoms have little influence on the diffusion of nickel atoms. The solid state diffusion rule of nickel atom on surface of the low carbon steel is D_Ni=-3.53×10^-21T⁴+1.75×10^-17T³ -3.22×10^-14T²+2.60×10^-11T -7.81×10^-9. During solid state diffusion at 973-1373 K, the average interdiffusion coefficient of nickel atoms increases first, then decreases and then increases with the increase of temperature. The crystal structure has a great influence on the diffusion of nickel atoms, and the diffusion speed of nickel atoms in the body centered cubic crystal structure is obviously higher than that in the face centered cubic crystal structure.

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