Misorientation Analysis of Plastic Deformation of Austenitic Stainless Steel by EBSD and X-Ray Diffraction Methods

Abstract

The misorientation introduced into an austenitic stainless steel (SUS 316) by plastic deformation was masured with the electron back scattering diffraction (EBSD) and the X-ray diffraction (XRD) techniques. Three parameters related to miorientation distribution, i.e. grain orientation spread (GOS), grain average misorientation (GAM) and kernel average misorientation (KAM), were calculated from the orientation measurements by EBSD. The misorienation between neighboring measured points, KAM, was larger close to the grain boundary where the slip propagation was difficult. The average of misorientation between neighboring points within one grain is GAM. The GAM value averaged over the measured reagion increased proportionally with the plastic strain to about 20%, and leveled off at higher strains. The average of the misorientation spread within one grain, GOS, also showed similar increase like GAM. The total misorientation of a grain measured by XRD also showed a proportional increase with the plastic strain to about 10%, and it was difficult to measure the total misorientation above that strain because Debye ring became continuous ring. Both EBSD and XRD can be used as a tool to measure the plastic strain in the local area, and the limit of strain to be measured was 30% for the former and 10% for the latter.