Grain Refinement and Elimination of Hot Cracks due to Application of Electromagnetic Stirring in Commercial Aluminum Alloy Welds

In this work the physical effects of electromagnetic stirring (EMS) during welding on the microstructure of some commercial 6xxx and 7xxx series of aluminum alloys are investigated. Experiments are carried out with standard GTA equipment in combination with a current carrying coil providing an axial magnetic field. In order to achieve the maximum grain refining effect, a:range of optimal stirring parameters is established. It is then demonstrated that the optimal parameters are in the frequency range of 2 to 15 Hz and the corresponding magnetic field intensities of 10 to 25 mT. These parameters are then applied to reduce susceptibility of these alloys to hot cracking. This paper concludes that by application of EMS to GTA welding of aluminum alloys it is possible to refine the grain structure and reduce the hot cracking susceptibility of these alloys, especially those employed in the aerospace and automotive industries.