焊后时效处理对7020铝合金应力腐蚀倾向影响  

Effect of post-weld aging on stress corrosion sensitivity of 7020 aluminum alloy

作　　者：周永东 龚兰芳 刘梓屹 Zhou Yongdong;Gong Lanfang;Liu Ziyi(CRRC Zhuzhou Locomotive Co.,Ltd.,Zhuzhou Hunan 412005,China)

机构地区：[1]中车株洲电力机车有限公司,湖南株洲412005

出　　处：《金属热处理》2023年第6期80-84,共5页Heat Treatment of Metals

基　　金：中车株机科研项目(2021KJ112);中车株机工艺研发项目(2023GY073)。

摘　　要：7020铝合金焊接接头常常因应力腐蚀而开裂。针对上述问题,本文将采用自然时效、单级时效、双级过时效、回归再时效等焊后热处理工艺处理相同焊接工艺试样。通过对经不同后处理的试样进行表面微观形貌和微观结构分析、慢应变速率拉伸应力腐蚀试验及断口分析,研究不同焊后时效处理对7020焊接接头抗应力腐蚀开裂性能的影响。结果表明,回归再时效后的试样气孔数量减少,无沉淀析出带宽化,晶界析出物消失,晶内析出物细化从而展现出最低的应力腐蚀倾向。Welded joints of 7020 aluminum alloy are often cracked due to stress corrosion.In order to address the above problems,sample of the same welding process were treated by post-weld heat treatment processes of natural aging,one-step aging,two-step over-aging,retrogression and re-aging(RRA).By analyzing the surface micromorphology,microstructure,slow strain rate tensile stress corrosion test results and fracture of the specimens undergone different post-treatments,the effect of different post-weld aging treatment on the stress corrosion cracking resistance of the 7020 welded joints were studied.The results show that after the regression re-aging treatment,the number of pores is decreased,the precipitates free zone is widened,the grain boundary precipitates disappear,and the grain precipitates are refined,by which the welded joints of the 7020 aluminum alloy obtains the lowest stress corrosion tendency.

关 键 词：7020铝合金 焊接接头 焊后热处理 回归再时效 应力腐蚀 

分 类 号：TG166.3[金属学及工艺—热处理]