Effect of rotation speed on the microstructure and mechanical properties of friction stir welded joints of 6061 aluminum alloy and pure copper dissimilar metals

转速对6061铝合金/纯铜异种金属搅拌摩擦焊接头组织与性能的影响 Effect of rotation speed on the microstructure and mechanical properties of friction stir welded joints of 6061 aluminum alloy and pure copper dissimilar metals 秦佳琛 QIN Jiachen 1 2 first-author 张大童 ZHANG Datong 1 corresp dtzhang@scut.edu.cn 谭锦红 TAN Jinhong 2 尤佳庆 YOU Jiaqing 2 赵运强 ZHAO Yunqiang 2 华南理工大学机械与汽车工程学院国家金属材料近净成形工程技术研究中心 华南理工大学机械与汽车工程学院国家金属材料近净成形工程技术研究中心 National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials,School of Mechanical and Automotive Engineering,South China University of Technology National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials,School of Mechanical and Automotive Engineering,South China University of Technology 广东省科学院中乌焊接研究所 广东省科学院中乌焊接研究所 Ukraine Institute of Welding,Guangdong Academy of Sciences,China Ukraine Institute of Welding,Guangdong Academy of Sciences,China 采用搅拌摩擦焊技术对4 mm厚6061-T6铝合金和纯铜进行连接,研究转速对铝铜异种金属接头组织与力学性能的影响。结果表明,当焊接速度为30 mm/min、搅拌头转速在1 200～1 800 r/min的范围内,可以获得表面成形良好、无缺陷的铝铜异种金属接头。大量破碎的铜被搅入焊核区,形成了组织结构复杂的区域。通过EDS和XRD分析,在焊核区内发现了Al 2 Cu、Al 4 Cu 9 和Al Cu金属间化合物。在界面处,铝和铜发生相互扩散形成金属间化合物层,随着转速的提高,化合物层逐渐变厚。由于晶粒细化、固溶强化作用以及金属间化合物的生成,异种接头的焊核区平均显微硬度值高于铝铜两侧平均硬度,并且在焊核区出现硬度峰值点。随着转速的增加,接头抗拉强度呈现先增大后减小的趋势,所得最优接头抗拉强度为183 MPa,达到铜母材的71.8%,断裂位置位于铝侧热影响区,断裂方式为韧性断裂。 In this paper,6061-T6 aluminum alloy and pure copper are welded by friction stir welding and the effect of rotation speed on the microstructure and mechanical properties of dissimilar joints is studied. When the welding speed is 30 mm/min and the rotation speed is in the range of 1 200 r/min to1 800 r/min,sound joints without defects can be obtained. The complex structures are formed in the nugget zone where a large number of broken Cu particles are stirred into. Al 2 Cu,Al 4 Cu 9 and AlCu intermetallic compounds are found in the nugget zone.The intermetallic compound layer is formed by mutual diffusion between aluminum and copper at the interface. With the increase of rotation speed,the compounds layer gradually becomes thicker. Due to the grain refinement,solid solution strengthening and the appearance of the IMCs,the average microhardness of the nugget zone is higher than that of aluminum and copper sides,and the microhardness peak appears in the nugget zone.Meanwhile,the tensile strength of the joint firstly increases and then decreases. The tensile strength of the optimal joint is 183 MPa and the joint efficiency is up to 71.8% of Cu BM. The fracture occurs in the heat affected zone of Al side,and the fracture mode is a ductile fracture. 6061铝合金 纯铜 搅拌摩擦焊 微观组织 力学性能 6061 aluminum alloy pure copper friction stir welding microstructure mechanical properties TG407 广州市科技计划项目(201807010063) 2022-03-08 2 51