EBSD study of microstructure evolution during axisymmetric hot compression of 304LN stainless steel

In the present work, axisymmetric compression tests were carried out on 304LN stainless steel at temperatures of 900 degrees C, 1000 degrees C and 1100 degrees C at strain rates of 0.01 s(-1), 0.1 s(-1) and 1 s(-1). Electron back scatter diffraction (EBSD) technique was used to characterize the microstructure, qualitatively as well as quantitatively. The resultant microstructures were a mixture of both elongated deformed and equi-axed recrystallized grains for samples deformed at 900 degrees C. For samples deformed at 1000 degrees C and 1100 degrees C, the microstructures are almost fully recrystallized with a high fraction of Sigma 3 twin boundaries. Partitioning of these microstructures, based on grain orientation spread (GOS) approach, was done to separate the deformed grains and the recrystallized grains. The obtained recrystallization fraction was used to estimate the flow stress value between the peak stress and the steady state stress. A good agreement between the predicted and the experimental flow stress value was observed.