预回复对固溶-T652处理超高强铝合金挤压材组织与性能的影响

摘要

The effect of pre-recovery treatment on microstructure and properties of Al-12.5Zn-3.6Mg-1.2Cu- 0.2Zr-0.06Sr aluminum alloy extrusion treated by solid solution –T652 treatment was studied. The results show that the pre-recovery treatment ((250℃, 24 h)+(300℃, 6 h)+(350℃, 6 h)+(400℃, 6 h)) can improve the dislocation density of the alloy significantly, refine the grain size (from 11.14 to 5.25 μm), reduce the average angle grain boundaries (from 17.81° to 12.57°) and increase the percentage of low angle grain boundaries (from 66.2% to 76.4%), but reduce the hardness and tensile strength slightly. Pre-recovery treatment enhances inter-granular corrosion performance, the maximum corrosion depth decreases from 247.7μm to 138.0μm. Quantitative analysis results show that the decrease of the alloy strength can be attributed to the decline of aging precipitation strengthening. The promotion of corrosion resistance can be due to the improvement of the proportion of low angle grain boundary and the coarsening of precipitates.%研究预回复对固溶-T652处理超高强铝合金Al-12.5Zn-3.6Mg-1.2Cu-0.2Zr-0.06Sr挤压材组织与性能的影响。结果表明：合金在固溶-T652处理前预回复处理((250℃，24 h)+(300℃，6 h)+(350℃，6 h)+(400℃，6 h))能明显提高合金的位错密度，显著细化合金晶粒(平均晶粒尺寸从11.14μm下降到5.25μm)，降低晶界平均角度(从17.81°下降到12.57°)，提高低角度晶界所占比例(由66.2%提高到76.4%)，但硬度和强度略有下降。预回复处理能显著改善合金的抗晶间腐蚀性能，最大晶间腐蚀深度由247.7µm降为138.0µm。定量分析结果表明：合金强度的降低可归因于时效沉淀强化效果的降低；抗腐蚀性能的提高可归因于低角度晶界比例的提高和晶界析出相的粗化。