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研究了不同热处理工艺下7A55铝合金淬火预拉伸(W51)板材的力学性能、腐蚀性能、电导率变化以及相应的微观组织特点。用正交实验分析双级时效工艺,结果表明7A55铝合金双级时效的四因素中第二级时效温度和时间是影响最终性能的主要因素。淬火预拉伸7A55合金板材最佳双级时效热处理工艺分别为:T7651:121℃×5h+170℃×6h,T7451:121℃×5h+160℃×14h。电镜观察结果表明,T7451、T7651时效时晶内析出半共格的η′相和η相,并有不同程度粗化,晶界为断续分布的粗大η平衡相。这种微观结构能有效的提高7A55合金板材的电导率和腐蚀性能,同时使合金具有较高强度。
The mechanical properties, corrosion properties, electrical conductivity and the corresponding microstructure of 7A55 aluminum alloy pre-hardened (W51) sheet under different heat treatment processes were studied. The orthogonal experiment was used to analyze the two-stage aging process. The results show that the second stage aging temperature and time of the four-stage 7A55 aluminum alloy are the main factors affecting the final performance. The best two-stage aging heat treatment process for 7A55 alloy plate with quenched and pre-stretched is respectively T7651: 121 ℃ × 5h + 170 ℃ × 6h, T7451: 121 ℃ × 5h + 160 ℃ × 14h. Electron microscopy results show that the microstructures of η ’phase and η phase are precipitated in the microstructure of T7451 and T7651. Coarsening and intergranular coarse equiaxed phases exist in the grain boundaries. This microstructure can effectively improve the conductivity and corrosion properties of 7A55 alloy plate, while making the alloy with higher strength.