焊后热处理对7075铝合金搅拌摩擦焊接头组织及性能的影响  

Effect of Post-weld Heat Treatment on Microstructure and Properties of Friction Stir Welded 7075 Aluminum Alloy Joints

作　　者：崔少朋 朱浩[1,2] 郭柱[1,2] 王彦红[1,2] 赵熠朋 

机构地区：[1]河北省交通工程材料重点实验室,河北石家庄050043 [2]石家庄铁道大学材料科学与工程学院,河北石家庄050043

出　　处：《石家庄铁道大学学报（自然科学版）》2015年第4期104-108,共5页Journal of Shijiazhuang Tiedao University(Natural Science Edition)

基　　金：河北省自然科学基金(2012210001);河北省教育厅基金(2010204);河北省高等学校科学技术研究重点项目(ZD2010209);教育部科学技术研究重点项目(211022);河北省高校重点学科建设项目资助

摘　　要：使用搅拌摩擦焊(FSW)设备对厚度为6 mm的7075高强铝合金平板进行对接试验。采用不同热处理工艺(固溶温度、时效时间)对接头进行热处理,并对不同热处理工艺下的接头进行微观组织观察和显微硬度测试。研究结果表明:7075铝合金FSW接头由焊核区(WNZ)、热机影响区(TMAZ)及热影响区(HAZ)组成,WNZ为细小均匀的等轴晶组织;热处理后接头WNZ部分晶粒发生粗化;随着固溶温度的升高,晶粒粗化程度增大;随着时效时间的延长,WNZ晶粒粗化程度变化不明显;FSW接头显微硬度分布呈"W"型,热处理后接头显微硬度均有不同程度的升高,随着时效时间的延长,接头的显微硬度先增大后减小;固溶温度490℃、时效温度120℃、时效时间24 h是厚度为6 mm的7075铝合金FSW接头的最佳热处理工艺参数。The butt welding was carried out on the 7075 aluminum alloy plate of 6ram thickness using friction stir welding （FSW）. Post-weld heat treatments with different parameters （solution temperature, aging time） were performed on the FSW joints. The microstructure of the welded joints under different heat treatment processes was observed and the micro-hardness was tested. The results show that the FSW joints are made up of weld nugget zone （WNZ）, thermo-mechanical affected zone （TMAZ） and heat affected zone （HAZ）. The WNZ exhibits equiaxed fine grains, which are coarsened after heat treatment. With increased solution temperature, the grain size increases. With increased aging time, no obvious differences are observed on the coarsened grains. The microhardness of the FSW joint shows an asymmetric ＂W＂ shape and increases to some extent after heat treatment. With increased aging time, the microhardness of the joints firstly increases and then decreases. For the 7075 aluminum alloy FSW joint of 6ram thickness, the best heat treatment parameters include the heating temperature of 490 ℃, solution temperature of 120℃ and the aging time of 24 h.

关 键 词：7075铝合金 搅拌摩擦焊 焊后热处理 微观组织 显微硬度 

分 类 号：TG457.14[金属学及工艺—焊接]