Effect of Cross Rolling on the Edge Microstructure and Formability of AZ31 Magnesium Alloy

Abstract:

The AZ31B magnesium alloy sheet was subjected to a hot rolling test at a temperature of 250℃ to 400℃ at a rate of 0.5 m/s, and four different cross rolling paths were selected to reduce the edge cracks during the deformation. The hot rolling structures and textures were modified for controlling the edge crack generation. The macroscopic morphology, microstructure and texture of the magnesium alloy plate obtained by different rolling processes were analyzed by scanning electron microscopy (SEM) and electron backscattering (EBSD). The results show that, the edge crack of the magnesium plate decreases with the increase of the temperature, and there was almost no crack appearance in the magnesium alloy plate obtained by the RII rolling path at 400℃. The angles between Edge crack and rolling direction were approximately 45 degrees, and the edge of the magnesium plate formed a “O” with the widest part of 129μm under rolling path II, which meant that It will difficult to further expand to both sides. After the multi-cross rolling, the grains were obviously refined, and most of the grains had a completely dynamic recrystallization. The number of low-angle-grain-boundaries decreased with the changes of different rolling path, and the intensity of the base texture was reduced from 23.68 to 7.62. More fine grains can not only produce a larger grain boundary, but also weaken the base texture, and obviously inhibit the expansion of the crack, control the formation of edge crack.

Key words:AZ31 Mg alloy; edge crack; cross rolling; texture weakening