AN EBSD STUDY OF THE MICROSTRUCTURAL EVOLUTION DURING SUPERPLASTIC DEFORMATION OF A FINE-GRAINED AZ31 MAGNESIUM ALLOY

摘要

An EBSD study of the microstructural evolution during superplastic deformation was conducted on a commercial AZ31 magnesium alloy sheet with initial grain size less than 21μm. Before deformation, a strong (0001) basal fiber texture existed in the as-received sheet. With deformation, it was found that the grain size increased depending on deformation temperatures, and the pre-existing fiber texture was not destroyed during deformation although obvious grain boundary sliding was observed. At 673K, grain boundary sliding was the main deformation mechanism, while at 773K, grain boundary sliding accommodated by slip is the main mechanism. Considering the existence of the strong basal fiber texture during deformation, the strengthening in < 1120 > direction observed from the pole figures indicated that, instead of slip on basal plane, slip along < a > direction on non-basal plane was very important.