Effects of ultrasonic assisted friction stir welding on flow behavior, microstructure and mechanical properties of 7N01-T4 aluminum alloy joints

doi:10.1016/j.jmst.2019.12.007

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	Effects of ultrasonic assisted friction stir welding on flow behavior, microstructure and mechanical properties of 7N01-T4 aluminum alloy joints
	Zhang, Zhiqiang; He, Changshu; Li, Ying; Yu, Lei; Zhao, Su; Zhao, Xiang
刊名	JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
	2020
卷号	43 页码:1-13
关键词	TUNGSTEN INERT-GAS SUBGRAIN FORMATION WELDED-JOINTS AL/MG ALLOYS VIBRATION DEFORMATION TEMPERATURE EVOLUTION TOOL THICKNESS
DOI	10.1016/j.jmst.2019.12.007
英文摘要	Conventional friction stir welding (FSW) and ultrasonic assisted friction stir welding (UAFSW) were employed to weld 6-mm thick 7N01-T4 aluminum alloy plates. Weld forming characteristics and material flow behavior in these two different welding processes were studied and compared. Ultrasonic vibration was applied directly on the weld in axial direction through the welding tool. Metal flow behavior, microstructure characteristics in the nugget zone (NZ) and evolution of the mechanical properties of naturally aged joints were studied. Results show that the ultrasonic vibration can significantly increase the welding speed of defect-free welded joint. At the rotation speed of 1200 rpm, the UAFSW can produce defect-free welded joints at a welding speed that is 50% higher than that of the conventional FSW. Ultrasonic vibrations can also improve surface quality of the joints and reduce axial force by 9%. Moreover, ultrasonic vibrations significantly increase the volume of the pin-driven zone (PDZ) and decrease the thickness of the transition zone (TZ). The number of subgrains and deformed grains resulting from the UAFSW is higher than that from the FSW. By increase the strain level and strain gradient in the NZ, the ultrasonic vibrations can refine the grains. Ultrasonic energy is the most at the top of the NZ, and gradually reduces along the thickness of the plate. The difference in strengths between the FSW and the UAFSW joints after post-weld natural aging (PWNA) is small. However, the elongation of the UAFSW is 8.8% higher than that of the FSW (PWNA for 4320 h). Fracture surface observation demonstrates that all the specimens fail by ductile fracture, and the fracture position of the UAFSW joint changes from HAZ (PWNA for 120 h) to NZ (PWNA for 720 and 4320 h). (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.
学科主题	Materials Science ; Metallurgy & Metallurgical Engineering
内容类型	期刊论文
源URL	[http://ir.nimte.ac.cn/handle/174433/19792]
专题	2020专题
作者单位	He, CS (corresponding author), Northeastern Univ, Key Lab Anisotropy & Texture Mat, Shenyang 110819, Peoples R China.
推荐引用方式 GB/T 7714	Zhang, Zhiqiang,He, Changshu,Li, Ying,et al. Effects of ultrasonic assisted friction stir welding on flow behavior, microstructure and mechanical properties of 7N01-T4 aluminum alloy joints[J]. JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY,2020,43:1-13.
APA	Zhang, Zhiqiang,He, Changshu,Li, Ying,Yu, Lei,Zhao, Su,&Zhao, Xiang.(2020).Effects of ultrasonic assisted friction stir welding on flow behavior, microstructure and mechanical properties of 7N01-T4 aluminum alloy joints.JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY,43,1-13.
MLA	Zhang, Zhiqiang,et al."Effects of ultrasonic assisted friction stir welding on flow behavior, microstructure and mechanical properties of 7N01-T4 aluminum alloy joints".JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY 43(2020):1-13.