Effects of electromagnetic stirring on particle mixing during GTA welding of Al-Mg-Si matrix composites

In this paper the results are presented of a study dealing with the influen ce of electromagnetic stirring of the weld pool during GTA welding of the c omposite 6061/Al2O3/10p. Attention is focussed on the mixing behaviour of t he particles when welding with filler material (Al 5wt.% Si). Bead-on-plate welding experiments were carried out under different stirring conditions. After welding, cross-sections were made of each weld and these cross-sectio ns were examined visually and using optical microscopy. The degree of mixin g of the particles in the welds obtained was expressed in terms of a mixing parameter. It appears that the best mixing results are obtained with a mag netic induction higher than 20 mT and a stirring frequency of around 2 Hz a nd that the hardness of the stirred welds (after T6 heat treatment) does no t significantly deviate from that of the base material. On the basis of the results obtained it can be concluded that electromagnetic stirring can be successfully applied in the case of welding composite material under practi cal conditions.