Crystallographic orientation dependence of ε martensite transformation during tensile deformation of polycrystalline 30% Mn austenitic steel

The dependence of the ε martensite transformation on the crystallographic orientation during a tensile test of metastable high-manganese austenitic steel, Fe-30 mass% Mn, with a polycrystalline microstructure was studied. The ε martensite plates were formed after the steel yielded by slipping, and the volume fraction of the ε martensite increased with increasing strain. No significant orientation dependence of the martensite formation was observed in the early stage of the tensile deformation, but when the sample was further strained up to about 30%, the tensile directions of the grains with martensite were preferentially found to be nearly parallel to the 〈111〉 direction of the austenite matrix. This orientation dependence corresponded with the orientation preferable for the development of local misorientations as detected by EBSD.