In the current work, using tensile tests, we evaluate the hydrogen embrittlement behavior of a 1.5 GPa dual-phase (DP) steel consisting of ~75% martensite. Contrary to previous studies of DP steel with ultimate tensile strength (UTS) ≤1.2 GPa, a predominant brittle fracture is observed in the DP steel in the absence of hydrogen. Conventionally, in the absence of hydrogen, ferrite is reported to arrest cracks, resulting in a ductile fracture. However, ferrite undergoes {100} brittle cleavage cracking. Furthermore, the morphology of the martensite crack is found to have an influence on ferrite {100} cleavage cracking. The micro-mechanisms are presented in detail. Subsequently, we investigated the effect of hydrogen on the degradation of tensile properties. Hydrogen caused a significant deterioration of UTS, from 1.5 GPa to 0.9 GPa. The damage mechanisms of hydrogen-induced fracture are discussed in detail.
EXTENDED ABSTRACT