Effect of grain boundary characters on low cycle fatigue behavior of hydrogen charged high-Mn TWIP steels

Abstract

High-manganese twinning-induced plasticity (TWIP) steels receive great attention nowadays due to their excellent combination of tensile strength and elongation. However, TWIP steels often reveal hydrogen embrittlement (HE), i.e., hydrogen delayed fracture, leading to the catastrophic failure of the structural components. In order to prevent or suppress HE, high stacking fault alloying element such as Al is added in the TWIP steels. Recently, an alternative approach is used by the application of grain boundary engineering, a method to increase the fraction of coincidence site lattice (CSL) by imposing a small amount of strain and annealing. The aim of this study is to investigate the effect of grain boundary engineering on low cycle fatigue (LCF) properties of hydrogen charged TWIP steels. Results showed that LCF properties of GBE processed TWIP steels were similar to those of as-received TWIP steels in the uncharged condition, while the degradation of low cycle fatigue life of the former was not significant in the hydrogen charged condition. Such improvement was attributed to lowered grain boundary energy and random boundary discontinuity.