轧制温度对AZ31镁合金板材组织和性能的影响

Influence of rolling temperature on microstructure and properties of AZ31 magnesium alloy sheet

以多向锻造AZ31镁合金为板坯进行高应变速率轧制成形,研究轧制温度对板材组织与力学性能的影响。结果表明:镁合金高应变速率轧制成形前期,孪生作用增强,形成大量的{1012}拉伸孪生和{1011}-{1012}二次孪生;变形后期,由于孪生诱发动态再结晶的作用,合金晶粒组织明显细化。在压下量为80%的高应变速率轧制下,轧制温度为250~400℃时,轧制板材组织均发生了完全再结晶,平均晶粒尺寸随着轧制温度的升高从6.97μm增加至8.13μm,但由于轧制板坯的初始晶粒尺寸较小,晶粒尺寸随着轧制温度的升高变化较小;轧制板材的抗拉强度和伸长率均高于315 MPa和25%,表明高应变速率轧制工艺可以在较宽的温度区间内制备力学性能稳定的镁合金板材。

The sheet blank of AZ31 magnesium alloy after multi-directional forging was rolled at high strain rate, and the influences of rolling temperature on microstructure and mechanical properties of sheet metal were studied. The results show that in the early stage of high strain rate rolling, the twinning effect is enhanced to form a large number of stretch twinning ({1012}) and secondary twinning ({1011}-{1012}) In the later stage of deformation, the grain structure of alloy is obviously refined due to the dynamic recrystallization induced by twinning. Under the high strain rate rolling with the reduction of 80% and the rolling temperature of 250-400 ℃, the microstructure of rolled sheet is completely recrystallized, and the average grain size increases from 6.97 μm to 8.13 μm with the increasing of rolling temperature. But due to the small initial grain size of rolled sheet, the grain size changes little with the increasing of rolling temperature, and the tensile strength and elongation of rolled sheet are higher than 315 MPa and 25%, indicating that the high strain rate rolling process can produce the magnesium alloy sheet with stable mechanical properties in a wide temperature range.