TWI

Friction stir welding (FSW) experiments were performed on Al-based alloys prepared by direct-chill casting and continuous casting, and the influence of intermetallic particles and process parameters on onion ring zone morphology and microstructure was investigated. The alloys studied were 2024-T351 (Al, 3.8-4.9%Cu, 1.2-1.8%Mg), 5251-H34 (Al, 1.94%Mg, 0.35%Mn), 5754-O (Al, 2.6-3.6%Mg, 0.5%Mn) and 5083-H116 (Al, 4.22%Mg, 0.57%Mn). FSW was conducted on sheets (thickness 2.3-6.3 mm) at rotation speeds of 200-500 rpm and feed rates of 75-500 mm/min. Microstructural characterisation was undertaken for parent metal and weldments using optical microscopy, SEM and TEM. The occurrence of coarse and fine grain bands, grain boundary precipitation and coarse particle segregation is discussed.

6th International Symposium, 10-13 Oct 2006, Session 10B: Metallurgy I, Paper 04