Hydrogen embrittlement of three high-manganese steels tested by different hydrogen charging methods

In this study the hydrogen embrittiement characteristics of three high-manganese steels were tested using different hydrogen charging methods, and the results were compared with various Mn-containing steels. The results showed that the hydrogen embrittiement susceptibility of the high-manganese steels increased with increasing inherent strength because deformation mechanisms, such as deformation twinning, e-martensite transformation, and shear- or micro-band formation, enhanced their sensitivity to hydrogen-induced cracking. The different hydrogen charging methods also affected their ability to achieve the critical hydrogen concentration needed for hydrogen-induced cracking under the stress fields of each microstructure. The relative reduction in ductility for different charging methods usually increased in the order of ex-situ electrochemically-charged, ex-situ high-pressure thermally-charged, and in-situ environment tensile testing, although it was somewhat dependent on the charging, testing and specimen conditions. Based on the results of the three high-manganese steels, it was found that the high-pressure thermally-charged steel specimens had higher relative reductions in ductility because a larger amount of hydrogen was uniformly injected into the steel specimens, which promoted hydrogen-induced cracking under smaller strain than that of the electrochemically-charged steel specimens.