TWI

A friction stir spot welding process was employed to fabricate dissimilar joints between 6016 aluminium alloy (Al, 1-1.5%Si, 0.25-0.6%Mg) and galvanised HSLA 280 phosphorus-hardened cold rolled steel (0.08%C, 1.3%Mn, 0.1%Ti, 0.08%Al, 0.09%P), and the effects of weld geometry and the presence of Al-Fe intermetallic compounds on mechanical strength were investigated. The parameters varied during welding were probe penetration depth and rotational speed. Cross-sectional microstructures were observed by optical microscopy and SEM. Mechanical properties were characterised by tensile shear and tensile cross tests, and residual stresses were determined by neutron diffraction. Issues discussed include hanging zone geometry, formation of intermetallic compounds and the microhardness values of different Al-Fe phases.

7th International Symposium, 20-22 May 2008, 9A: Dissimilar Materials, Paper 03