TWI

With regard to the application of AA 2219 aluminium alloys to space launch vehicle propellant storage tanks, an investigation is presented into the influence of process parameters (tool rotational speed, shoulder downward force and weld transverse speed) on the properties of cylindrical welds fabricated by friction stir welding (FSW). Specimens comprised rolled plates (thickness 7 mm) of AA 2219-T87 alloy (Al, 6.42%Cu, 0.38%Mn). Experiments were conducted at tool driving forces of 27-35 kN, rotational speeds of 300-500 rpm and welding speeds of 200-350 mm/min. Metallographic analysis was undertaken using optical microscopy and SEM observations as well as microhardness measurements. Mechanical properties were characterised by tensile testing with an electromechanical controlled universal tensile machine. The FSW process and parameters were optimised for both fixed pin tool and retractable pin tool arrangements. Issues discussed include the transition from weld nugget to thermomechanically affected zone and the effects of tool pin offset on the retracting and advancing sides.

9th International Symposium, 15-17 May 2012, Session 2A: Applications I, Paper 03