Suppressed martensitic transformation under biaxial loading in low stacking fault energy metastable austenitic steels

The effect of uniaxial/biaxial loading on the martensitic transformation of a low stacking fault energy, metastable austenitic stainless steel was studied by in-situ neutron diffraction on cruciform-shaped/dogbone samples. Uniaxial loading favors the martensitic transformation following the sequence gamma -> epsilon -> alpha', where at low strains epsilon-martensite is the precursor of alpha'. During equibiaxial-loading, the evolving texture suppresses the formation of 5-martensite and considerably less alpha'-martensite is observed at high strains. The results are discussed with respect to the deformation textures, the loading direction and the mechanism of the epsilon-martensite transformation. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd