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Friction Stir Welding of 7075 Aluminum Alloy

Mirazizi, Meysam | 2008

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39170 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Kokabi, Amir Hossein
  7. Abstract:
  8. In this research, Friction stir welding (FSW) of 7075-O and 7075-T6 aluminum alloys was performed to investigate the effects of the base material conditions, effects of process parameters on the FSW characteristics and optimum parameters which lead to best mechanical properties of joints. The experimental results indicated that the base material condition has a significant effect on weld morphologies, weld defects, and mechanical properties of joints. The optimum parameters were 1230 rpm and 60 mm/min for 7075-O and 1230 rpm and 100mm/min for 7075-T6. Also, Double welded friction stir welding of 7075 aluminum alloy was performed to investigate the effects of the second pass of weld on the microstructure, hardness and yield strength of the first pass. In addition, the effect of pin length -that influences the amount of overlapping of two stir zones- on mechanical properties and microstructure of two pass was studied. Tensile test and Shear Punch Test (SPT) were conducted to determine mechanical properties of joints. Experimental results indicated that second pass of weld has significant effects on microstructure, hardness and yield strength of the first pass and the hardness and yield strength of first pass decreased. Also, somewhat overlapping of two pass in the middle of the joints decreased the mechanical properties of them noticeably.
  9. Keywords:
  10. Friction Stir Welding ; Aluminum Alloy 7075 ; T6 Heat Treatment ; Double-Welded Joints

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