层道排布对6005A铝合金MIG焊接头微观组织及力学性能的影响  

Effect of Layer Arrangement on Microstructure and Mechanical Properties of 6005A Aluminum Alloy MIG Joints

作　　者：李帅贞 韩晓辉 吴来军 刘裕航 王鹏 宋晓国[2,3] 檀财旺 LI Shuaizhen;HAN Xiaohui;WU Laijun;LIU Yuhang;WANG Peng;SONG Xiaoguo;TAN Caiwang(CRCC Qingdao Sifang Co.,Ltd.,Qingdao 266111,Shandong,China;State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology,Harbin 150001,China;Shandong Provincial Key Laboratory of Special Welding Technology,Harbin Institute of Technology at Weihai,Weihai 264209,Shandong,China)

机构地区：[1]中车青岛四方机车车辆股份有限公司,山东青岛266111 [2]哈尔滨工业大学先进焊接与连接国家重点实验室,哈尔滨150001 [3]哈尔滨工业大学(威海)山东省特种焊接技术重点实验室,山东威海264209

出　　处：《材料导报》2022年第17期153-157,共5页Materials Reports

基　　金：国家自然科学基金(52005132);山东省自然科学基金(ZR2019PEE038)。

摘　　要：本工作研究了熔化极惰性气体保护焊(MIG)焊层道排布方式对6005A铝合金接头组织及力学性能的影响。首先,基于两层两道、两层三道、三层三道这三种层道排布方式得到了焊缝成形良好的10 mm厚6005A铝合金对接接头;然后,通过焊接热循环对比了热影响区(HAZ)的峰值温度,采用电子背散射衍射(EBSD)、透射电子显微镜(TEM)等研究了各个接头热影响区的组织转变;最后,通过硬度测试和拉伸试验等测试方法研究了各个接头的力学性能。结果表明,不同的层道排布方式使HAZ经历不同的焊接热循环而呈现不同的微观组织及力学性能,且位于HAZ的软化区是6005A铝合金多层多道MIG接头最薄弱部位。三层三道接头HAZ发生不完全再结晶,使晶粒呈现轧制态特征;两层两道HAZ发生完全再结晶,使晶粒呈现等轴化特征;两层三道接头HAZ晶粒再结晶程度介于两层两道和三层三道之间。热影响区强化相β″发生过时效是接头软化的主要原因。在三种层道排布方式中,三层三道接头的线能量最低、高温停留时间最短,故HAZ过时效程度最低,拉伸强度和硬度损失最少,其平均拉伸强度可达211 MPa,明显高于两层三道的183 MPa和两层两道的161 MPa。The effects of metal inert gas(MIG) welding layer and pass arrangements on the microstructure and mechanical properties of 6005A aluminum alloy joints were studied. High-quality butt joints were obtained with different welding layer arrangements, including two layer-two pass, two layer-three pass and three layer-three pass. The peak temperature of heat-affected zones(HAZ) was compared by welding thermal cycles, and the microstructure transformation in the heat-affected zones was studied by electron backscattering diffraction(EBSD) and transmission electron microscopy(TEM). Moreover, the microhardness and tensile strength of welded joints were examined. The results indicate that the softening zone located in the HAZ is the weakest part of the 6005A aluminum alloy multi-layer and multi-pass MIG joint. Different microstructures and mechanical properties were obtained in the HAZ with different welding layer arrangements, through different welding thermal cycles. The rolled characteristic of grains was observed in incomplete recrystallization HAZ of the three-layer and three-pass welded joint, while equiaxed grains were obtained in the complete recrystallization HAZ of the two-layer and two-pass welded joint, and the recrystallization extent of grains in the HAZ of the two layer-three pass welded joint was between those of the three layer-three pass and two layer-two pass welded joints. Besides, the overaging of the HAZ strengthening phase β″ leads to joint softening. Among the three types of welding layer arrangements, the three-layer and three-pass welding joints has the lowest energy input and the shortest high-temperature residence time, resulting in the lowest degree of HAZ overaging as well as the lowest strength and hardness. In this case, the average tensile strength of three-layer and three-pass welding joints is 211 MPa, which is higher than that(183 MPa) of two-layer and two-pass welding joints and that(161 MPa) of two-layer and three-pass welding joints obviously.

关 键 词：6005A铝合金 多层多道焊 层道排布 析出相 接头软化 

分 类 号：TG444.7[金属学及工艺—焊接]