Effect of small tool pin profiles on microstructures andmechanical properties of 6061 aluminum alloy by friction stir welding
(1. School of Materials Engineering, Universiti Malaysia Perlis, Taman Muhibah-Jejawi-Arau, Perlis 02600, Malaysia;
2. Department of Chemical Engineering, College of Engineering, University of AL-Qadisiya, AL-Qadisiya, Iraq;
3. Centre for Low Carbon Transport in Cooperation with Imperial College London,
Institute for Vehicle System Engineering, Universiti Teknologi Malaysia, Skudai 81310, Malaysia)
2. Department of Chemical Engineering, College of Engineering, University of AL-Qadisiya, AL-Qadisiya, Iraq;
3. Centre for Low Carbon Transport in Cooperation with Imperial College London,
Institute for Vehicle System Engineering, Universiti Teknologi Malaysia, Skudai 81310, Malaysia)
Abstract: The effect of small tool pin profiles on the microstructures and mechanical properties of 6061 aluminum alloy joints using friction stir welding (FSW) technique was investigated. Three different tool pin profiles: threaded tapered cylindrical (T1), triangular (T2) and square (T3) were used to produce the joints. The results indicate that the weld joints are notably affected by joining with different tool pin profiles. The triangular tool pin profile produces the best metallurgical and mechanical weld properties compared with other tool pin profiles. Besides, the lowest tensile strength and microhardness are obtained for the joint friction stir welded with square tool pin profile. It is observed that the smaller tool pin profile and shoulder diameter lead to narrow region of heat affected zone (HAZ) and a desired level of softening. The fracture surface examination shows that the joints are also affected when welding with different types of tool pin profiles. The fracture surface shows that the triangular specimen fails with a ductile fracture mode during the tensile test, while the brittle fracture modes are observed in the joints fabricated with other tool pin profiles (T1 and T3).
Key words: friction stir welding; small tool pin profile; mechanical properties; aluminum alloy; grain size