摘要
通过扫描电镜和透射电镜研究焊后热处理时间和温度对6061铝合金双脉冲MIG焊接接头显微组织的影响。采用硬度测试和拉伸实验研究热处理时间和温度对6061铝合金双脉冲MIG焊接接头力学性能的影响。结果显示,时效时间和温度对显微硬度的影响较大。增加时效温度有助于缩短峰值时效时间。未时效状态下,焊接接头内部存在许多位错和少量析出相组织。随着时效温度和时间的增加,接头处位错密度逐渐降低,同时,沉淀相逐渐析出并长大。当时效温度增加至200℃时,焊接接头处析出较大的Q'相,此时焊合接头的硬度达到最大。
6061 aluminum alloy T-joints were welded by double-pulsed MIG welding process. Then, the post-weld heat treatment was performed on the welded T-joints. The weld microstructure under different aging temperature and time was investigated by transmission electron microscopy and scanning electron microscopy. The mechanical properties were examined by hardness test and tensile test. The results showed that the micro-hardness was sensitive to heat treatment temperature and time. Increasing temperature was beneficial to the shortening of peak aging time. There were a large number of dislocations and few precipitates in the welded joints. With the increase of post-weld heat treatment temperature and time, the density of dislocation decreased. Meanwhile, the strengthening phase precipitated and grew up gradually. When the post-weld heat treatment temperature increased up to 200℃, large Q' phases were observed. And they were responsible for the peak value of the micro-hardness in the welded joints.
作者
易杰
王冠
李世康
刘志文
龚艳丽
Jie YI;Guan WANG;Shi-kang LI;Zhi-wen LIU;Yan-li GONG(College of Mechanical Engineering,Hunan Industry Polytechnic,Changsha 410208,China;State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,Hunan University,Changsha 410082,China;Qiuzhen College,Huzhou University,Huzhou 313000,China;College of Mechanical Engineering,University of South China,Hengyang 421001,China)
基金
Projects(2019JJ70077,2019JJ50510) supported by the National Science Foundation of Hunan Province,China
Project(31665004) supported by Open Fund of State Key Laboratory of Advanced Design and Manufacture for Vehicle Body,China
Projects(18B552,18B285) supported by Scientific Research Fund of Hunan Provincial Education Department,China
关键词
6061铝合金
双脉冲MIG焊
焊后热处理
组织演变
力学性能
6061 aluminum alloy
double-pulsed MIG welding
post-weld heat treatment
microstructure evolution
mechanical property