Study On Rolling Process Of AZ31 Mg Alloy Plate Fabricated By Horizontal Continuous Casting

In this paper, technology of AZ31 mg alloy horizontal continuous casting(HCC) was introduced, macrostructure and microstructure characteristics of AZ31 mg alloy plates formed by horizontal continuous casting were studied, and effects of homogeneous heat treatment on microstructures and mechanical properties of AZ31 plates were also analyzed. Based on the hot rolling experiment under 400℃,effects of rolling process on microstructures and mechanical properties of AZ31 plates were investigated, and microstructure evolution and grain refinement mechanism were discussed. Based on X-ray diffraction, texture evolution of AZ31 mg alloy during rolling process was studied,anisotropy properties of sheets were investigated, while relationship between anisotropy and texture configuration was also analyzedThe results showed that there were surface equiaxed grains, columnar grains existed in the AZ31 mg alloy HCC plate, while dendritic segregation and second phases Mg17A112 also existed in the microstructure of the plates. After homogeneous heat treatment, dendritic segregation and the second phases disappeared which result in the decreasing of tensile strength and increasing of yield strength and the elongation.As rolled under 400℃at different rolling reductions of 10%, 20%, 30%, 40% and 50%, effects of strain intensity and rolling reduction on microstructure and mechanical properties of rolled AZ31 mg alloy sheets were studied. The results exhibited that, with the increasing of strain intensity, nucleus amount of dynamic recrystallization was increased and more grains were refined. In the beginning and middle stages of rolling process, mechanical properties of the sheets increased with the increasing of strain intensity. At the end of the rolling process, with the increasing of strain intensity, yield and tensile strength increased while elongation decreased due to the low temperature caused by heavy heat diffusion of the sheets. Compared the results of tensile tests and microstructure, rolling reduction have no obviously effect on microstructure and mechanical properties of the AZ31 mg alloy sheets.Based on the results of X-ray diffraction analysis, effects of strain intensity and rolling reduction on textures of rolled AZ31 mg alloy sheets were studied. The results showed that, in the beginning and middle stages of rolling process, the intensity of {0002} basal component increased with the increasing of strain intensity, while lightly decreased at the end because of grain-boundary sliding. Compared sheets made by different rolling reductions, in the beginning of the rolling process, high rolling reduction lead to a lower {0002} basal texture intensity, while at the end, {0002} basal texture intensities of all the sheets made by different rolling reduction became similar. During rolling process, texture intensity of sheet surface was higher than the center, while the difference between textures of surface and center became smaller and smaller as the rolling goes and finaly became the same. After the rolling process, ideal plate textures existed in the finishing rolled sheets, while no obvious anisotropy was found.