TWI

Friction stir welding (FSW) was employed to fabricate overlap joints in thin AA 7075-T6 aluminium alloy (Al, 5.1-6.1%Zn, 2.1-2.9%Mg, 1.2-2%Cu) sheets (thickness 0.8 mm) coated with an anticorrosive aluminium layer and the microstructure and mechanical properties of the weldments were investigated. Single run and double run welding were performed using a 3-axis CNC milling machine with truncated cone shape or truncated oblique cone shape monolithic tools made from hot worked tool steel. Cross-sectional microstructure was observed by optical microscopy. Mechanical properties were characterised by microhardness measurements and tensile tests. Issues discussed include the use of double run welding with a symmetric tool to prevent hooking defects, cold laps and thinning defects and the capability of the tool with an asymmetric pin to increase the degree of material mixing.

11th International Symposium, 17-19 May 2016, Poster Session, Paper 01