时效制度对7B04高强铝合金力学及腐蚀性能的影响

采用常规力学性能、标准紧凑拉伸、电导率、慢应变速率拉伸(SSRT)及剥落腐蚀测试等手段,研究了不同热处理状态下7B04铝合金预拉伸板的力学及腐蚀性能。结果表明,合金的强度、韧性和腐蚀性能与时效制度密切相关。单级峰时效(T6)状态下合金的强度最高,但是其抗应力腐蚀(SCC)性能及断裂韧性最低;双级过时效(T74和T73)状态下材料的断裂韧性和抗SCC性能明显提高,但是其强度牺牲较多;与T6相比,RRA时效处理可明显提高合金的抗SCC性能,且强度牺牲较少,仅下降2%左右,同时断裂韧性也有一定提高。

Influence of Aging Tempers on Mechanical and Corrosion Properties of a High Strength 7B04 Aluminium Alloy Pre-Stretched Plate

The mechanical and corrosion properties of 7B04 Al alloy pre-stretched plate with various heat treatments were investigated using mechanical properties testing,compact testing,conductivity testing,slow strain rate testing and exfoliation corrosion testing and so on. The results showed that the strength,toughness and corrosion properties of the alloy were greatly concerned with the aging tempers. Peak strength could be achieved,when T6 heat treatment was applied to the alloy,but with the lowest stress corrosion cracking (SCC) resistance and fracture toughness. The overaging T74 and T73 could improve SCC resistance and toughness of the alloy,but sacrifice its strength in great value. The retrogression and re-aging (RRA) processes provided a method for increasing the SCC resistance of the alloy without sacrificing its strength,and the fracture toughness could also be increased somewhat comparing with T6 temper.