Effect of deformation and annealing on the formation and reversion of ε-martensite in an Fe-Mn-C alloy

Microstructure and texture evolution during cold rolling and subsequent annealing were studied in an Fe-22 wt Mn-0 376 wt % C alloy During rolling the deformation mechanisms were found to be dislocation slip, mechanical twinning, deformation-induced epsilon-martensite transformation and shear banding At higher strains, the brass-type texture with a spread towards the Goss-type texture dominated A decrease in the Cu- and S- components was attributed to the preferential transformation to epsilon-martensite in Cu- and S-oriented grains. The texture of epsilon-martensite was sharp and could be described as {1 1 2 9} < 3 3 6 2 > The orientation relationship {1 1 1}(epsilon)//{0 00 1}(epsilon) and < 1 1 0 >(epsilon)//< 1 1 2 0 >(epsilon) between (epsilon)-martensite and austenite was observed but only certain variants were selected On subsequent annealing, the epsilon-martensite transformed reversely to austenite by a diffusionless mechanism Changes in length along rolling, normal and transverse directions on heating were anisotropic due to a combination of volume expansion and shape memory effects The S-texture component increased significantly due to transformation from the epsilon-martensite (C) 2010 Acta Materialia Inc Published by Elsevier Ltd All rights reserved