TWI

Dissimilar welded joints between AW 6061-T6 aluminium alloy (Al, 0.93%Mg, 0.59%Si, 0.5%Fe) and AZ31B-H24 magnesium alloy (Mg, 2.55%Al, 0.79%Zn) were fabricated by friction stir welding and the influence of process parameters on their microstructure and mechanical properties was investigated. Welding was performed using an MTS ISTIR PDS machine with an H13 tool steel shoulder and an MP159 pin. A design of experiments methodology was employed to analyse parameters such as rotational speed (400-1600 rpm), travel speed (30 or 60 mm/min), offset, location of samples (advancing or retreating side) and tilt angle (1 or 3 degrees). Welded joint microstructure was observed by optical microscopy. Mechanical properties were characterised by microhardness measurements and transverse tensile tests. Issues discussed include lack of penetration defects due to insufficient pin length, no defect weld formation under different heat input conditions and the effect of brittle intermetallic compounds on microhardness.

11th International Symposium, 17-19 May 2016, Session 7B: Dissimilar, Paper 03