Effect of Prior Deformation Above Md Temperature on Tensile Properties of Type 304 Metastable Austenitic Stainless Steel

In this study, room temperature tensile properties of type 304, a metastable austenitic stainless steel, prior rolled above M-d temperature (200 degrees C and 300 degrees C) are compared with mill-annealed and material prior rolled at room temperature (25 degrees C). Strain-induced martensite that formed during the tensile tests, followed using in-situ using magnetic measurements, display kinetics that vary with prior deformation temperature and strain. Scanning Electron Microscopy and Electron Backscattered Diffraction studies provided direct evidence for shear band formation during prior deformation. Kinetics of strain-induced martensite is found to fit the Olson-Cohen equation modified to include the prior deformation strain and martensite formed during prior deformation. The systematic changes observed in the model parameters of the modified Olson-Cohen equation are explained. The strain hardening in the material is analyzed and correlated with changes in the rate of formation of strain-induced martensite with respect to strain.