TWI

Square butt welds of AA 7075-T6 sheet (thickness 1.3 or 3.2 mm) to AA 7075-T6 extrusions were fabricated by friction stir welding (FSW) procedures incorporating the controlled introduction of defects, and the impact of the defects on joint mechanical properties was assessed from tensile and fatigue tests. The defects studied were controlled pre-weld gap, controlled thickness mismatch, lack of penetration, tool wear and minimum recrystallised grain structure in extruded stiffener. Ultimate tensile stress, breaking load, yield stress and elongation were determined from static tensile tests, and fatigue life was evaluated from tests conducted at a cycling frequency of 10 or 30 Hz. Weld cross-sections were observed by optical metallography. The importance of FSW parameters and optimised tool design is discussed.

6th International Symposium, 10-13 Oct 2006, Session 4A: Quality I, Paper 03