Competition of mechanisms contributing to the texture formation in metastable austenitic steel under compressive load

Abstract

The interplay of microstructural mechanisms controlling the deformation-induced martensitic phase transformations and the texture formation in all phases of a metastable austenitic Cr-Mn-Ni steel was investigated using in situ synchrotron radiation diffraction under uniaxial compression and ex situ electron backscatter diffraction. With increasing deformation, the originally fully austenitic steel transformed to a mixture of γ-austenite, ε-martensite and α´-martensite. The face centred cubic γ-austenite formed a fibre texture {110} with respect to the deformation direction. The texture degree increased progressively with increasing deformation. The hexagonal close packed ε-martensite was preferentially oriented with the reciprocal direction {101¯3} along the load axis. The texture degree was nearly independent of the deformation extent. The body centred α´-martensite formed a mixed texture {100} & {111} along the deformation direction. The texture component {100} was very strong in the early stages of the α´-martensite formation, but it deteriorated with increasing deformation. The texture evolution is explained by the competition between the transformation texture, several deformation-induced mechanisms, which are highly sensitive to the local orientation of the grains with respect to the acting force, like the stacking fault formation and martensitic transformation in austenite, and the variant selection in both martensites and the twinning of α´-martensite.