Assessment of the degradation in mild structural steel using electron backscatter diffraction (EBSD) technique

Abstract

This paper reports the degradation assessment of mild steel during the plastic tensile process. The electron backscatter diffraction (EBSD) technique was adopted in this study. The orientation maps showed that with the increase of tensile strain, the grain surface become wrinkled, and the deviation level of intragranular orientation also increased. Meanwhile, the parameters based on the image quality of the Kikuchi bands (i.e. BC and MAD) as well as the crystallographic orientation (i.e. LAGBs content, GND density, GOS, and GROD) can be used to evaluate the degradation degree of the mild steel. The results showed that the change of BC and MAD was significant at the end of plastic stage, but was not sufficiently distinctive at the early stage; Meanwhile, the LAGBs content and GND density increased evidently during the plastic tensile. Compared with the former, the GND density exhibited stronger regularity and better evaluation effect; Besides, a general upward trend of GOS and GROD was observed at this tensile process. However, the GROD changed less at the certain plastic stage. Compared with GROD, the GOS exhibited a relatively better evaluation effect; To sum up, the GND density and GOS are the better indicators for evaluating the degradation degree of mild steel.