Microstructural evolution of Mo?W?V alloyed hot-work die steel during high-temperature tempering

LI Shuang; SHI Yan-lin; YANG Xiao-cai; SHI Yong-liang; WANG Zhen; ZHANG Shi-xian; SHI Yuan-ji; WU Xiao-chun

doi:10.13374/j.issn2095-9389.2019.06.04.003

Volume 42 Issue 7

Jul. 2020

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Article Navigation > Chinese Journal of Engineering > 2020 > 42(7): 902-911

LI Shuang, SHI Yan-lin, YANG Xiao-cai, SHI Yong-liang, WANG Zhen, ZHANG Shi-xian, SHI Yuan-ji, WU Xiao-chun. Microstructural evolution of Mo?W?V alloyed hot-work die steel during high-temperature tempering[J]. Chinese Journal of Engineering, 2020, 42(7): 902-911. doi: 10.13374/j.issn2095-9389.2019.06.04.003

Citation:

LI Shuang, SHI Yan-lin, YANG Xiao-cai, SHI Yong-liang, WANG Zhen, ZHANG Shi-xian, SHI Yuan-ji, WU Xiao-chun. Microstructural evolution of Mo?W?V alloyed hot-work die steel during high-temperature tempering[J]. Chinese Journal of Engineering, 2020, 42(7): 902-911. doi: 10.13374/j.issn2095-9389.2019.06.04.003

Citation:

LI Shuang, SHI Yan-lin, YANG Xiao-cai, SHI Yong-liang, WANG Zhen, ZHANG Shi-xian, SHI Yuan-ji, WU Xiao-chun. Microstructural evolution of Mo?W?V alloyed hot-work die steel during high-temperature tempering[J]. Chinese Journal of Engineering, 2020, 42(7): 902-911. doi: 10.13374/j.issn2095-9389.2019.06.04.003

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Microstructural evolution of Mo?W?V alloyed hot-work die steel during high-temperature tempering

doi: 10.13374/j.issn2095-9389.2019.06.04.003

1.
Hebei College of Industry and Technology, Shijiazhuang 050091, China
2.
Hebei Material Fine Crystal Preparation Technology Innovation Center, Shijiazhuang 050091, China
3.
Nanjing Institute of Industry Technology, Nanjing 210046, China
4.
School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China

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Corresponding author: E-mail: sylyyyy@163.com
Received Date: 2019-06-04
Publish Date: 2020-07-01

Abstract

Abstract

Hot-work die steels are widely used to meet the requirements of industrial applications in which the steels must endure high temperature and mechanical loads, such as the hot stamping of very-high-strength steel. In the field of hot-stamping technology applications, the tool materials must have excellent high-temperature performance, such as the high-temperature stability of the microstructure. Research on hot-stamping die materials began somewhat late in China because high-quality die steel products had typically been imported. A new type of hot-stamping die steel with high thermal conductivity and high wear resistance was developed to meet the requirements of hot-stamping technology. In this study, we used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to determine the high-temperature tempering performance and microstructural characteristics of this new Mo?W?V alloyed hot-work die steel. Based on the results, we derived the precipitation and evolvement rules of the carbides in the new type hot-stamping die steel during the tempering process, which indicate that the new Mo?W?V alloyed test steel has an excellent secondary hardening property. We find the hardness of the microstructure to increase after tempering at 500 ℃–600 ℃; however, at tempering temperatures above 600 °C, the matrix obviously softens and the hardness of the test-steel microstructure decreases. The hardness of the test die steel is strongly linked to the segregation, precipitation and growth of the alloy carbides in the matrix. No alloy carbide precipitation is observed at tempering temperatures below 560 ℃; however, M₂C-type carbide precipitation is observed at tempering temperatures higher than 560 ℃. MC-type alloy carbide is observed in the test-steel matrix at tempering temperatures up to 600 ℃. At tempering temperatures above 620 ℃, the M₂C-type alloy carbides transform into M₆C-type alloy carbides and the hardness curve of the test steel sharply declines. The MC-type and M₆C-type alloy carbides are the main carbides in the matrix of the new Mo?W?V alloyed hot-work die steel.
- die steel,
- heat treatment,
- alloy carbide,
- microstructure,
- transmission electron microscopy

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References(18)

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