Effect of Welding Conditions on Weld Zone Temperature and Mechanical Properties of Friction Stir Welded AZ61 Magnesium Alloy Sheet

• Published in: Metals and materials international Vol. 30; no. 10; pp. 2853 - 2870
• Main Authors: Lee, Woo Geun, Go, Yohan, Kim, Jae-Yeon, Sun, Seung-Ju, Lim, Jae-Yong, You, Bong Sun, Kim, Jung-Seok, Kim, Young Min
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Institute of Metals and Materials 01.10.2024; Springer Nature B.V; 대한금속·재료학회
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Crystal defects; Electron back scatter; Engineering Thermodynamics; Friction stir welding; Grain size; Heat and Mass Transfer; Heat treating; Integrity; Low temperature; Machines; Magnesium base alloys; Magnetic Materials; Magnetism; Manufacturing; Materials Science; Mechanical properties; Metal sheets; Metallic Materials; Microstructure; Microtexture; Optical microscopy; Optical properties; Processes; Solid Mechanics; Surface defects; Thermomechanical properties; Welded joints; Welding parameters; 재료공학; Mechanical properties; Temperature; Friction stir welding (FSW); Texture; Magnesium alloy
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-024-01681-1

The peak temperature range of the weld zones of the AZ61 alloy sheet during FSW varied from 450.1 to 569.4 °C depending on the welding conditions. The evaluation of FSW integrity suggests that both void defects and tunneling cavities observed at the conditions of 400 rpm-100 mm/min and 400 rpm-300 mm/min are caused by insufficient material fluidity because of the low temperature inside the welds. However, tunnel- and surface defects at the condition of 1600 rpm-100 mm/min are caused by a high peak temperature of 569.4 °C, which leads to mass loss at the outer boundary of the stir zone because of excessive flash and local melting during the rotation of the tool. To enhance the integrity and mechanical properties of the weld, the welding parameters should be controlled such that the peak temperature in the weld zones is in the range of 493.2–508.9 °C. The microstructure of the FSWed AZ61 joints was analyzed in terms of grain size and micro-texture by optical microscopy and Electron back-scattered diffraction. The fracture behaviors and mechanical properties of the FSWed AZ61 joints were closely related to the microstructure of the thermomechanical affected zone (TMAZ), and it was discussed based on the grain size and average Schmid factor in the TMAZ. Graphical Abstract