TWI

Dissimilar butt joints between aluminium alloys and steel or an AZ91 magnesium alloy (Mg, 9.39%Al, 0.85%Zn) were fabricated by ultrasound enhanced friction stir welding (USE-FSW) and their microstructure, mechanical and corrosion properties were investigated. The aluminium alloys were AW 6061 (Al, 0.89%Mg, 0.64%Si, 0.21%Cu) or AC-48000 (Al, 11.86%Si, 1.04%Mg, 1.02%Cu, 0.99%Ni) and the steels were DC04 (0.04%C, 0.3%Mn, 0.49%Al) or C45 (0.45%C, 0.24%Si, 0.71%Mn). A Taguchi design of experiment method was employed to optimise process parameters: rotational speed 300-1250 rpm, feed rate 30 or 50 mm/min. tilt angle of 2 or 3 deg. and welding force of 2.2-12 kN for the various material combinations. Microstructure was observed by optical microscopy. Tensile tests and X-ray radiography were carried out to analyse joint quality. Corrosion was examined using scanning Kelvin probe, open circuit potential and potentiodynamic polarisation measurements.

12th International Symposium, 26-28 Jun 2018, Session 7A: Techniques II, Paper 01