Role of copper and aluminum additions on the hydrogen embrittlement susceptibility of austenitic Fe-Mn-C TWIP steels

The role of alloying elements on the hydrogen embrittlement (HE) susceptibility of a Fe-18Mn-0.6C alloy was investigated by in situ tensile tests and characterized by the ductility loss associated with intergranular fracture. Under cathodic polarization an improvement of HE resistance is related to the SFE increase with Cu or Al additions reducing the stress-strain and H localization at grain boundaries, which prevents H-induced intergranular cracking. At rest potential, beneficial effects of Cu and Al are related to their influence on hydrogen absorption during the corrosion process. However, residual phosphorus strongly reduces the beneficial effect of aluminum.