Heat Treatment of Metals ›› 2024, Vol. 49 ›› Issue (7): 106-112.DOI: 10.13251/j.issn.0254-6051.2024.07.016

• MATERIALS RESEARCH • Previous Articles     Next Articles

Hydrogen embrittlement of V+Ti microalloyed Mn-Cr bainitic forging steel

Zhou Lei1, Wang Ying1, Zhang Yongjian2, Zhao Xiaoli2, Hui Weijun2   

  1. 1. Special Steels Division, Nanjing Iron & Steel Co., Ltd., Nanjing Jiangsu 210035, China;
    2. School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China
  • Received:2023-12-22 Revised:2024-04-02 Online:2024-07-25 Published:2024-08-29

Abstract: Hydrogen desorption and hydrogen embrittlement (HE) behavior of a V+Ti microalloyed Mn-Cr bainitic forging steel in the as-forged and 500 ℃ tempered conditions were studied by using electrochemical pre-hydrogen-charging, hydrogen thermal analysis (TDA) and slow strain rate tensile (SSRT) testing combined with SEM, TEM and EBSD microstructural analyses. The results show that the blocky martensite/austenite (M/A) constituents decompose with the precipitation of nano-sized (V,Ti)(C,N) and cementite particles, which causes a decrease of tensile strength while a significant increase of yield strength. The result of TDA reveals that most of absorbed hydrogen is diffusible hydrogen and the hydrogen content in the tempered specimen is slightly lower than that of the as-forged specimen. The HEI expressed by the relative loss of notch tensile strength before and after hydrogen-charging significantly decreases from 31.8% for the as-forged specimen to 12.8% for the tempered specimen, which is mainly due to the microstructural changes caused by the tempering treatment.

Key words: bainitic forging steel, granular bainite, hydrogen embrittlement, tempering, microstructure

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