Measurement of Plastic Strain Distribution by Electron Backscatter Diffraction

Abstract

Electron backscatter diffraction (EBSD) in conjunction with scanning electron microscopy was used to assess the distribution of the plastic strain on a microstructural scale (local plastic strain) induced in stainless steel. The local misorientation, which is a misorientation between neighboring pixels, was investigated in order to represent the degree of the local plastic strain. Accuracy of the measurement of the local misorientations was improved by a technique, in which an average of crystal orientation was calculated for several data measured from the same domain. It was shown that the local misorientation was inhomogeneous and localized in the vicinity of grain boundaries. The distribution of the local misorientations followed the log-normal distribution and the mean value correlated well with the macroscopic plastic strain induced in specimens. By using the correlation between the averaged local misorientation and the plastic strain, the distribution of local plastic strain was estimated. This procedure for estimating local plastic strain was applied to measurements of non-uniform plastic stain in notched specimens and its validity was shown by comparing with results of finite element analysis.