Microstructural Analysis and Texture Evolution of the CVCEDed AZ31 Magnesium Alloy by Hot Rolling

Grain refinement is one of the important methods to improve the performance of magnesium alloy sheets. This paper attempts to prepare the billets of AZ31 magnesium alloy sheets by continuous variable cross-section direct extrusion (CVCDE) and then prepare sheets by rolling. The results show that the average grain size of the sheets rolled from extruded products by CVCDE with 2 interim dies reduced by 30% and the tensile strength increased by 12.6% compared with the sheets rolled from extruded products by traditional extrusion (CE), which is related to the dislocation multiplication in the corresponding conditions. The high dislocation density hinders the plastic deformation of the material, which is one of the internal factors that cause the increase in the strength of the material and the decrease in the plasticity. In addition, the basal surface of a lot of grains of the sheets rolled from extruded products by CVCDE with 2 interim dies is parallel to the RD-TD plane and the strength of texture is high. Meanwhile, the value of average Schmid factor of the sheets rolled from extruded products by CVCDE with 2 interim dies along the rolling direction is lowest, which result in lower plasticity. The above research provides a new idea for the development of high-performance magnesium alloy sheets.