Effect of manganese content on the hydrogen embrittlement of twinning-induced plasticity (TWIP) steels under hydrogen charging and hydrogen environment

The hydrogen embrittlement behavior of two stabilized austenitic twinning-induced plasticity (TWIP) steels under high-pressure thermal hydrogen charging and hydrogen environment were investigated by slow strain rate tensile and fatigue crack growth tests. The results show that the two TWIP steels with Mn content (16% and 25%) do not produce strain-induced martensite after deformation, but both show a certain susceptibility to hydrogen embrittlement after hydrogen charging, in which the TWIP steel with higher Mn content shows weaker hydrogen embrittlement. This is mainly due to the high hydrogen embrittlement susceptibility of deformation twins. In the H2 environment, compared with slow strain rate tensile tests, fatigue crack growth tests is more likely to reflect the hydrogen embrittlement susceptibility of the TWIP steel, and the hydrogen environment is more likely to promote the crack growth of the TWIP steel with lower Mn content. This is related to the inter-granular cracking of TWIP steel with low Mn content under H2 environment. The increase of Mn content reduces the hydrogen diffusion coefficient and hydrogen solubility of TWIP steel, which is also one of the reasons for the weak hydrogen embrittlement of TWIP steel with high Mn content in hydrogen charging and hydrogen environment.