时效制度对7475铝合金组织与性能的影响

通过对不同时效制度下的常温拉伸性能、硬度、电导率、抗应力腐蚀性能、断裂韧性等性能测试及微观组织观察，分析不同时效制度对7475铝合金挤压型材的微观组织与性能影响。结果表明，单级峰值时效（T6）具有很高的强度，但抗应力腐蚀性能较差，主要是因为晶界析出物的性质所决定的；双极时效（T76、T73）由于晶界析出物呈粗大和弧立状分布，具有较好的抗应力腐蚀性能，但由于过时效晶内析出相尺寸增大，强度有较大程度的下降。同时实验表明，时效制度对7475挤压型材断裂韧性的影响并不大。

Effects of Ageing on Microstructure and Properties of 7475 Aluminium Alloy

alloy is a kind of aluminium alloy with high strength. It's mainly used for construction parts of airplane. The properties, such as tensile property at room temperature, hardness, conductivity, SCC, fracture toughness, and microstructure were systematically studied. It shows that the alloy has very high strength, but poor resistance to SCC at on-step peak ageing. The high resistance to SCC was gained at two-step ageing, a little loss of strength followed. The ageing parameters have little effect on KIC in these studies.