Hydrogen-Induced Martensitic Transformation and Twinning in Fe45Mn35Cr10Co10

Hydrogen embrittlement can occur in steels with metastable phases, due to activation of the hydrogen-enhanced decohesion mechanism upon transformation. Meanwhile, recent investigations suggest that alloys undergoing e-martensite transformation may exhibit resistance to hydrogen embrittlement. To better understand hydrogen effects in these alloys, we investigate the hydrogen-induced microstructural transformations in a metastable Fe45Mn35Co10Cr10 alloy. To this end, we electrochemically charge unstrained samples, quantify the hydrogen evolution by thermal desorption spectroscopy, and observe microstructural transformations by scanning electron microscopy techniques. Through these analyses, we find that the hydrogen-induced e-martensite formation is dependent on the crystallographic orientation of the austenite grains, and takes place preferentially along Σ3 boundaries. Further charging of hydrogen induces extension twinning within the martensite. We examine the microstructural factors influencing these transformations to better understand the hydrogen-microstructure interactions.