Atomic scale understanding of the role of hydrogen and oxygen segregation in the embrittlement of grain boundaries in a twinning induced plasticity steel

Twinning induced plasticity (TWIP) steels are high strength metallic materials with potential for structural components in e.g. automotive applications. However, they are prone to hydrogen embrittlement (HE) and galvanic corrosion. We investigated the susceptibility of a model Fe 27Mn 0.3C (wt%) TWIP steel towards HE and oxidation at the sub-nanometer scale by atom probe tomography. We measured segregation of hydrogen and oxygen at grain boundaries, which appears to be associated to a strong manganese depletion. Our study suggests a correlation between HE and oxidation mechanisms in TWIP steels, which we argue can combine to favor the previously reported hydrogen enhanced decohesion (HEDE) of grain boundaries.