변형률 속도에 따른 AZ31 Mg 합금의 집합조직 및 전위 거동 관찰

This study is concerned with the influence of strain rate on the plastic deformation behavior and microstructure variables of AZ31 magnesium alloy sheet. The tensile properties were measured at room temperature at a strain rate of 0.001 and 100 s-1 using a universal tensile testing machine and servo-hydraulic high-speed tensile test machine respectively. The microstructure was observed at strains of 5, 10, 15%, produced by tensile elongation. As the strain rate increased, the flow stress and the yield strength increased. The EBSD analysis showed that a texture of the (0001) basal plane was formed parallel to the rolled plate and texture was formed at random in the (10□0) non-basal plane. Double twinning was not observed and extension and contraction twinning were observed at all strain rate levels. The fraction of twin boundaries were increased as strain rate increased. TEM analysis determined that the dislocation density of the specimen strained by 1% at a strain rate of 100 s-1 was higher than that of a strain rate of 0.001 s-1. In addition, the dislocation was found at all strain rate levels. These results show that the deference in elongation of the AZ31 Mg alloy is dependent on strain rate. (Received October 4, 2019; Accepted March 18, 2019)