热变形温度对7055铝合金热处理组织和力学性能的影响(英文)

采用Gleeble-1500D热模拟试验机对7055铝合金进行多道次热压缩试验,并对热压缩试样进行T6热处理。采用TEM、OM观察热压缩试样与热处理试样的组织形貌,并对热处理7055-T6试样进行拉伸试验,研究变形温度对7055铝合金多道次热压缩后组织、热处理后的显微组织与力学性能的影响。结果表明:热变形温度不仅影响多道次热压缩后试样的组织,而且显著影响该合金热处理后的组织和力学性能。在本试验条件范围内,随着温度的升高,经多道次热压缩后试样的晶粒长宽比先减小然后增加,位错密度降低,亚晶尺寸增加,热压缩过程中发生再结晶;热处理后合金中再结晶晶粒体积分数先降低后增加。再结晶体积分数越小,合金的强度越高。当温度为400°C时,再结晶体积分数最小,约为45%,并且合金的抗拉强度和伸长率达到最大值。

Effect of deformation temperature on microstructure and mechanical properties of 7055 aluminum alloy after heat treatment

The multi-pass hot compression test of 7055 aluminum alloy was performed at different temperatures and then the samples were heat treated by T6 heat treatment. The compressed samples were analyzed by OM and TEM. The results reveal that the average aspect ratio of the grains in the specimens compressed first decreases and then increases, the dislocation density decreases and subgrain diameter increases with the increase of deformation temperature. The effects of deformation temperature on the microstructure and mechanical properties of 7055 aluminum alloy after heat treatment were investigated by means of OM and mechanical property test. The results indicate that the deformation temperature significantly influences microstructure and mechanical property of 7055 aluminum alloy. The volume fraction of recrystallization grains presents a “fall-rise” pattern with the deformation temperature rising. The mechanical properties get better when the volume fraction of recrystallization grains decreases. Moreover, the volume fraction of recrystallization grain has a minimum value, appropriately 45%, and the sample exhibits the highest strength and elongation at the deformation temperature of 400 °C.