Study on hydrogen embrittlement during low-temperature tempering process of high-strength steel

ZC Cheng and A Jiang and W Yu, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 109, 605-623 (2025).

DOI: 10.1016/j.ijhydene.2025.02.092

Substantial hydrogen embrittlement occurs in high-strength materials, thus deteriorating their service performance. To explain the hydrogen embrittlement phenomenon during low-temperature tempering, the effects of tempering temperature and the addition of vanadium (V) on hydrogen embrittlement susceptibility were characterized using hydrogen permeation test, slow strain rate tensile (SSRT) test, and thermal desorption spectroscopy (TDS) test, alongside microstructural analysis and molecular statics and dynamics simulations. Increasing the tempering temperature from 200 degrees C to 320 degrees C enhances the hydrogen diffusion behavior, thereby increasing the susceptibility to hydrogen embrittlement, with hydrogen embrittlement susceptibility index IHE increasing from 4 % to 19 %. Our findings reveal that the decomposition of martensite, the increase in the F/M phase interface, and the transformation of epsilon-carbide to cementite lead to an increase in diffusible hydrogen content. A high proportion of phase interfaces, small-angle grain boundaries, and a low fraction of Sigma 3 GBs are favorable for hydrogen-induced cracking (HIC). The addition of V influences hydrogen embrittlement in two ways: by inhibiting martensite decomposition and by forming VCN. The former has a more significant impact on hydrogen embrittlement.

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