A novel method to improve the integrity of friction stir welded joints of aluminum alloy: microstructure and mechanical properties. (17th May 2019)

• Record Type: Journal Article
• Authors: Guo, Chao; Liu, Wenming; Yan, Yinfei; Hou, Wentao; Huang, Guoqiang; Shen, Yifu
• Is Part Of: Materials research express. Volume 6:Number 8(2019)
• Publication Date: 2019-05-17
• Subjects: friction stir welding -- root flaws -- thickness reduction -- microstructure -- mechanical properties; Materials science -- Research -- Periodicals; Materials science -- Periodicals; 620.11
• DOI: 10.1088/2053-1591/ab1efd
• Languages: English
• ISSNs: 2053-1591

Abstract

Abstract: This paper aims to offer a novel friction stir welding (FSW) for improving the joint integrity. It uses the upper sheet and grooved backing plate to avoid thickness reduction and root flaws. The effect of process parameters on the microstructure and mechanical properties was investigated by Taguchi method. The results showed that thickness reduction and root flaws in the joints could be completely eliminated. The morphologies of stir zone (SZ) were able to be divided into typical stacked layers and onion ring structures. Besides, all the SZ contained fine equiaxed grains and its grain size increased as the ω /v ratio increased. The signal to noise (S/N) ratio showed the optimum parameters were rotational speed of 1000 rpm, welding speed of 65 mm min −1 and tilt angle of 2.5°, which reached the largest tensile strength of 238 MPa, approximately 84.1% of base metal (BM). The fracture morphology of the joint contained plenty of dimples, exhibiting typical ductile fracture.