Effect of tool offsetting on microstructure and mechanical properties dissimilar friction stir welded Mg-Al alloys

Joining and Welding Symposium

金属工艺学

Baghdadi, Amir Hossein^1 ; Mohamad Selamat, Nor Fazilah^1 ; Sajuri, Zainuddin^1

Department of Mechanical and Material Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, Bangi, Selangor

43600, Malaysia^1

关键词: Environmental pollutions;    Friction stir welding(FSW);    Joining techniques;    Lower temperatures;    Microstructure and mechanical properties;    Solid-state welding process;    Special applications;    Welding parameters;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/238/1/012018/pdf
DOI  :  10.1088/1757-899X/238/1/012018

来源: IOP

【 摘 要 】

Automotive and aerospace industries are attempting to produce lightweight structure by using materials with low density such as aluminum and magnesium alloys to increase the fuel efficiency and consequently reduce the environmental pollution. It can be beneficial to join Mg to Al to acquire ideal performance in special applications. Friction stir welding (FSW) is solid state welding processes and relatively lower temperature of the process compared to fusion welding processes. This makes FSW a potential joining technique for joining of the dissimilar materials. In this study, Mg-Al butt joints were performed by FSW under different tool offset conditions, rotation rates (500-600 rpm) and traverse speeds (20 mm/min) with tool axis offset 1 mm shifted into AZ31B or Al6061 (T6), and without offset. During the welding process AZ31B was positioned at the advancing side (AS) and Al6061 (T6) was located at the retreating side (RS). Defect free AZ31B-Al6061 (T6) dissimilar metal FSW joints with good mechanical properties were obtained with the combination of intermediate rotation rate and low traverse speed pin is in the middle. When tool positioned in -1 mm or +1 mm offsetting, some defects were found in SZ of dissimilar FSWed joints such as cavity, tunnel, and crack. Furthermore, a thin layer of intermetallic compounds was observed in the stir zone at the interface between Mg-Al plates. The strength of the joint was influenced by FSW parameters. Good mechanical properties obtained with the combination of intermediate rotational speed of 600 rpm and low travelling speed of 20 mm/min by locating Mg on advancing side when pin is in the middle. Also, Joint efficiency of the welds prepared in the present study was between 29% and 68% for the different welding parameters.