TWI

The microstructure of joints produced between dissimilar Al alloys by friction stir welding (FSW) was studied. FSW was performed for joining of 5083/6061 Al alloy workpieces of 5 mm thickness using a rotation speed of 1800 rpm and a welding speed of 60 mm/min. The composition of Al alloy 5083 was Al, 0.7%Si, 0.2%Fe, 0.02%Cu, 0.63%Mn, 4.8%Mg, 0.06%Cr, 0.02%Zn, 0.01%Ti and that of alloy 6061 was Al, 0.64%Si, 0.23%Fe, 0.3%Cu, 0.06%Mn, 0.96%Mg, 0.14%Cr, 0.06%Zn, 0.03%Ti. The joint microstructure was examined using optical microscopy, SEM and the SEM-electron back scatter pattern method. Vickers hardness was measured. Magnesium content in the parent metals and stir zone was measured by EPMA. The effects of annealing at 773 K on microstructure were examined. Grain refinement was observed in the stir zone and a laminated structure called "onion ring" was observed.

5th International Symposium, 14-16 Sep 2004, Session 9A: Dissimilar Materials, Paper 03