Effect of Welding Parameters on Microstructure and Mechanical Properties of Friction stir Spot Welded Aluminum Alloy

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Bagher Saghchi Khorasani, Ali | 2013

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 45124 (07)
University: Sharif University of Technology
Department: Materials Science and Engineering
Advisor(s): Kokabi, Amir Hossein
Abstract:
Friction stir spot welding (fssw) is a newly-developed solid state joining technology. In this study, normal fssw is applied to join the AlMg6 aluminum alloy sheets with 3 mm thickness and then the effect of the rotational speed and dwell time on microstructure and mechanical properties is discussed. The hardness profile of the welds exhibited a W-shaped appearance and minimum hardness was measured in the HAZ. The results of tensile/shear tests indicate that the joint strength increases and after a special rotational speed it decreases. Also the strength increases and after a special dwell time it decreases . At the rotational speed of 1500 rpm and dwell time of 6 sec, the tensile/shear strength reached the maximum of 8900 N. The microstructure and macrostructure of welded samples were observed. Also the fracture surface of samples were investigated by scanning electron microscopy, also the EDS analysis of precipitation was evaluated. Anneal process has been done on welded samples and the strength decreased through annealing. The mechanical properties such tensile/shear strength and fatigue strength shows better results than rivet ones
Keywords:
Friction Stir Spot Welding ; Welding Parameters ; Annealing ; Aluminum-Magnesium Alloy ; Riveted Joint

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