Anisotropy in the mechanical properties of AZ31 magnesium alloy after being compressed at high temperatures (up to 823 K)

The mechanical properties of AZ31 magnesium alloy compressed at high temperature (623–823 K) are investigated. The alloy was compressed along the rolling direction (RD) at a strain rate of 1 s−1. Optical microstructure observation and electron backscatter diffraction analysis reveal that the grain size and texture have a great influence on the mechanical properties. The fracture elongations (FE) of the compressed AZ31 Mg alloy samples are in the vicinity of 17% when the tensile direction is in the transverse direction (TD). When the tensile direction is in the normal direction (ND), the FE values grew abruptly at above 723 K. The yield stress (YS) value decreased linearly with the increasing deformation temperature along the TD. However, along the ND, the YS values decreased linearly at temperatures below 723 K but decreased more rapidly at temperatures higher than 723 K. The results show that mechanical anisotropy becomes stronger with the increasing temperature. This is because the orientations of the basal planes are rotated 90° from the ND to the RD at lower temperatures but about 45° from the ND to the RD after deformation at temperatures up to 823 K. The effects of grain size and texture on the mechanical properties are analyzed in detail.