TWI

2024-T3 aluminium alloy (Al, 4.4%Cu, 1.5%Mg) thin sheets (thickness 1 mm) were joined by friction stir welding (FSW), and the effect of process parameters (tool rotation speed and traverse rate) on the microstructure and mechanical properties of the welded joints was studied. Stir-on-plate welds were fabricated using a CNC FSW machine. Microstructure evolution for high and low heat input welds was observed by TEM and the relationships between TMAZ (thermomechanically affected zone) and HAZ microstructures, microhardness and tensile strength were studied. Fracture locations were examined for a series of welds and related to microstructure. The effect of S-phase coarsening, omega phase (Al2Cu) and Guinier-Preston-Bagaryatskii zone dissolution on hardness distribution is discussed. Effects of welding parameters on deformation rates and temperature experienced by the alloy during welding and consequences for microstructure and mechanical properties are discussed in detail.

6th International Symposium, 10-13 Oct 2006, Session 9A: Properties, Paper 02