TWI

Friction stir spot welding experiments were undertaken on AZ31 magnesium alloy (Mg, 3%Al, 1%Zn, 0.2%Mn) sheets (thickness 2 mm) in order to investigate the influence of a flame spray gun rapid preheating process on the microstructures and mechanical properties of the welded joints. After preheating at temperatures of 300-450 deg.C, welding was conducted at a rotational speed of 1500 rpm, dwell period of 5 s and plunge speed of 1 mm/s. Microstructure was observed by optical microscopy and the mean linear intercept method was employed to measure grain size. Room temperature lap/shear tensile tests were performed at a tensile speed of 1 mm/min. Issues discussed include grain size variations in stir zone, thermomechanically affected zone and HAZ and the effect of preheating temperature on tensile strength.

10th International Symposium, 20-22 May 2014, Session 3B: FSSW I, Paper 03