轧制温度和变形量对AZ31镁合金板材组织和硬度的影响

Effects of Rolling Temperature and Strain on Microstructure and Hardness of AZ31 Magnesium Sheets

研究了300、330、360℃3个轧制温度和3个道次不同变形量对AZ31镁合金组织和硬度的影响。试验结果表明:轧制变形使板材晶粒明显细化,硬度提高。在同一变形量下,随着轧制温度的升高,板材的晶粒呈长大趋势,硬度逐步下降,在330℃轧制时,板材的综合性能较好。在330℃轧制温度下,随着道次变形量的加大、轧制道次的增加,晶粒呈减小趋势,硬度逐步上升。在3个道次变形量均为40%时,轧制后的板材质量良好,没有出现裂边、裂纹现象,其组织均匀,晶粒细小。经过3个道次轧制后,板材的平均晶粒尺寸由原铸锭的120μm细化到3～4μm,板材的硬度(HRA)值由原铸锭的23.8提高到36.5。

The effects of rolling temperature at 300, 330, 360 ℃ and rolling strain at three passes on the microstructure and hardness of the AZ31 magnesium alloy sheets have been investigated. The results showed that the rolling can obviously refine the grain size in the magnesium sheets and improve its hardness. The grain size in the AZ31 magnesium alloy sheets would be coarsened with raising the rolling temperature at the same strain, which results in the decrease of hardness of the alloy sheets. However, the alloy sheets exhibit better comprehensive properties with rolling at 330 ℃. The grain size of the alloy sheets is decreased and the hardness is gradually increased with increasing strain and rolling passes at 330 ℃. After three passes with 40% strain per pass, the magnesium alloy sheets with uniformly distributed structure and fine grain size as well as crack-free inside or on the surface could be obtained, where the average grain size of the sheets are decreased from 120 μm to 3~4 μm, and the hardness (HRA) is increased from 23.8 to 36.5.