Mapping microstructure inhomogeneity using electron backscatter diffraction in 316L stainless steel subjected to hot plane strain compression tests

Abstract

The microstructure inhomogeneity in 316L stainless steel subjected to hot plane strain compression tests has been assessed using electron backscatter diffraction (EBSD). Two variables were investigated: the effect of strain rate and the effect of friction at the tool/specimen interface. Tests were performed isothermally at 950°C at nominal equivalent tensile strain rates of 0·01 and 1 s^?1. Low and high friction conditions have been simulated by applying both a glass based lubricant and a boron nitride spray respectively. Results suggest that friction causes a variation in microstructure from the surface to the midplane of the deformed specimen. Several methods used to quantify and represent this inhomogeneity are presented in the present paper. Electron backscatter diffraction measurement issues are discussed. A grain size mapping method using a two-dimensional moving average has been developed to overcome the difficulties associated with the visualisation of measurement results over large areas on EBSD maps. It has proved to be a powerful tool for the spatial statistics of large quantity data obtained by EBSD.