Measurement of local plastic strain distribution of stainless steel by electron backscatter diffraction

Electron backscatter diffraction in conjunction with scanning electron microscopy was used to assess the plastic strain on a microstructural scale (local plastic strain) induced in stainless steel deformed up to a nominal strain of 19.7%. Accuracy of the measurement of misorientations was improved by a technique called the Domain Averaging Method (DAM), in which an average of crystal orientation was calculated for several data measured from the same domain. It was shown that the misorientation evaluated using the crystal orientation of which accuracy was improved by DAM showed localized plastic strain in the vicinity of grain boundaries (GB). The distribution of misorientations followed a log-normal distribution and the mean value correlated well with the macroscopic plastic strain induced. By using the correlation between the misorientation and the plastic strain, the distribution of local plastic strain could be quantified. It was shown that the plastic strain becomes more than 15% locally under a macroscopic strain of 4.9%. A procedure for confirming the accuracy of the measurement is also suggested.