FRACTURE TOUGHNESS AND FATIGUE CRACK GROWTH TESTS OF FRICTION STIR WELDED PLATES

Friction stir welding has been demonstrated as a viable replacement to conventional fusion welding in various engineering applications. In most cases, the suitable welding parameters were selected based primarily on the tensile tests performed on welded test joints. In this project, a study on fracture toughness and fatigue crack growth of friction stir welded aluminium plates was performed. Two types of tests were conducted according to ASTM Standard Test Method E647-08 for fatigue crack growth and E399-08 for fracture toughness. The objectives of the project were to perform Fracture Toughness and Fatigue Crack Growth test on Friction Stir Welded aluminium plates, determining the plane strain fracture toughness KIC, establishing the rate of fatigue crack growth of the A6061 welded plates, and comparing those properties with non-welded A6061 plates. Friction stir welding was conducted using CNC milling machine with a tool pin of 8 mm length, pin diameter of 6 mm and shoulder diameter of 12 mm at 1600 rpm tool rotational speed, 12 mm/min weld speed and 12s dwell time. The results indicated that the friction stir welded plates exhibited lower fracture toughness and higher cracks propagation rate than non-welded plates.