TWI

A friction stir welding (FSW) methodology incorporating laser tracking and constant force control technologies was developed in order to fabricate large, thin-walled aircraft floor structures. The material chosen for study comprised sheet specimens (thickness 3 mm) of AA 7050-T7451 alloy (Al, 5.7-6.7%Zn, 1.9-2.6%Mg, 2-2.6%Cu). FSW experiments were undertaken on a moving gantry machine with constant force control at a rotational speed of 700 rpm, travel speed of 200 mm/min, tilt angle of 2.5 degrees and a welding force of 6.5-8.5 kN. Welded joint microstructure was observed by optical microscopy. Mechanical properties were characterised by tensile tests performed on a Z100 electronic universal material testing machine. Issues discussed include the influence of welding force on weldment tensile strength, the microstructure of weld nugget, HAZ and thermomechanically affected zones, and welding shrinkage mass.

9th International Symposium, 15-17 May 2012, Poster Session, Paper 09