TWI

Friction stir welding (FSW) experiments were performed to join two dissimilar aluminium alloys, AA-7075 (Al, 5.58%Zn, 2.48%Mg, 1.38%Cu) and AA-2024 (Al, 4.5%Cu, 1.36%Mg), in a butt configuration, and the microstructural and hardness characteristics of the stir zone were examined by SEM and EPMA (electron probe microanalysis). The process parameters employed were a rotational speed of 500 or 2500 rpm and a travel speed of 5.7 or 0.5 mm/s. SEM observations were conducted in the backscattered electron mode and Vickers hardness profiles were measured on a cross-section perpendicular to the welding direction. Issues discussed include zigzag boundary formation in low heat-input FSW, and onion ring structures and interface diffusion in high heat-input FSW.

6th International Symposium, 10-13 Oct 2006, Session 10B: Metallurgy I, Paper 01