Correlation Between Microstructure and Mechanical Properties of 2219-T8 Aluminum Alloy Joints by VPTIG Welding  

作　　者：Lan-Qiang Niu Xiao-Yan Li Liang Zhang Xiao-Bo Liang Mian Li 

机构地区：[1]College of Materials Science and Engineering,Beijing University of Technology,Beijing 100124,China

出　　处：《Acta Metallurgica Sinica(English Letters)》2017年第5期438-446,共9页金属学报（英文版）

基　　金：supported by the National Key Basic Research Program of China under Grant No.2012CB619503

摘　　要：In this study, 2219-T87 aluminum alloys were butt welded by the double-pass tungsten inert gas arc welding process. And the softening behavior of fusion zone（FZ） and heat-affected zone（HAZ） was evaluated with the analysis of welding temperature field, grain size, alloying element distribution and precipitates evolution. Results show that the two FZs are almost the weakest regions in the joint, where the microhardness value is 76 and 78 HV, respectively. Microhardness of the HAZ generally grows along with increasing distance from fusion line except a valley value at the distance of about 4.5 mm. The mean grain size of two FZs is about 74.4 and 79.2 lm, whereas 41.5, 44.9 and 43.4 lm for the two measured HAZs and base metal（BM）, respectively. There is about 60.4% and 54.2% Cu consumed in the coarse whitish particles of FZs that have little strengthening effect, while the percentage is about 24.6% of BM that is almost the same as HAZ. A large number of strengthening phases h0 distribute dispersively in BM, whereas hardly any precipitates exist in FZ and HAZ adjacent to FZ. So the coarsening of grain size, reduction and segregation of alloying element content, and the precipitate evolution are regarded as the main causes of softening in FZ, while the precipitate evolution is the main factor of softening in HAZ.In this study, 2219-T87 aluminum alloys were butt welded by the double-pass tungsten inert gas arc welding process. And the softening behavior of fusion zone（FZ） and heat-affected zone（HAZ） was evaluated with the analysis of welding temperature field, grain size, alloying element distribution and precipitates evolution. Results show that the two FZs are almost the weakest regions in the joint, where the microhardness value is 76 and 78 HV, respectively. Microhardness of the HAZ generally grows along with increasing distance from fusion line except a valley value at the distance of about 4.5 mm. The mean grain size of two FZs is about 74.4 and 79.2 lm, whereas 41.5, 44.9 and 43.4 lm for the two measured HAZs and base metal（BM）, respectively. There is about 60.4% and 54.2% Cu consumed in the coarse whitish particles of FZs that have little strengthening effect, while the percentage is about 24.6% of BM that is almost the same as HAZ. A large number of strengthening phases h0 distribute dispersively in BM, whereas hardly any precipitates exist in FZ and HAZ adjacent to FZ. So the coarsening of grain size, reduction and segregation of alloying element content, and the precipitate evolution are regarded as the main causes of softening in FZ, while the precipitate evolution is the main factor of softening in HAZ.

关 键 词：2219-T87 Aluminum alloy TIG welding Fusion zone Heat-affected zone Softening behavior 

分 类 号：TG457.14[金属学及工艺—焊接]