Effect of pre-aging on microstructure and stress corrosion resistance of 7020 aluminum alloy

作者：YANG Tao; YE Ling ying; SHAN Zhao jun; WANG Shao ling; DENG Yun lai; ZHANG Xin ming

来源：中国有色金属学报, 2016, 26(5).

• 7020 aluminum alloy
• pre-aging
• tensile property
• slowstrain rate tensile
• microstructure

After solution heat treatment at 470℃for 1h, the alloys were natural aged for 0hor168h and pre-aged at 65℃for 72hor168h, respectively. And then,the two-step aging ((90℃,8h)+(160℃,14h)) was conducted on these alloys. The effect of pre-ageing treatment on the tensile properties, resistances to stress corrosion and microstructures of 7020 aluminum alloy was investigated by tensile test, slow strain rate tensile (SSRT) test, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). 7020 aluminum alloy aged at 65℃for168h pre-ageing treatment has the highest tensile propertyRmof 397.4 MPa as well as the best stresscorrosion resistanceISSRTof ?0.003. The tensile property and stress corrosion resistance of alloy pre-ageing treatment at 65℃for72h are 387.6 MPa and 0.034. And it is comparable of that of natural aging 168h, withRmof 392.0 MPa andISSRTof 0.036. While the tensile property and stress corrosion resistance of alloy by direct two-step aging are the worst, withRmof 368.9 MPa andISSRTof 0.038. With the increase ofthepre-aging time, the size of intragranular precipitatesη′(MgZn2) inside grains decreases,the intermittent distribution degree of precipitates intragranular precipitatesη′(MgZn2) inside grains decreasesand the intermittent distribution degree of precipitatesη(MgZn2) at the grain boundaries increases.

• 单位
  中南大学