Confpaper

Microstructure in Dissimilar Friction Spot Weld of Al to Mg Alloys Observed by Stop-Action Technique

Abstract

In the current study, the formation of intermetallic compounds in dissimilar friction spot welding (refill friction stir spot welding) of AA5754 aluminum alloy to AZ31 magnesium alloy has been investigated by applying a stop action technique. The welding cycle was forced to stop during the dwell time, and subsequently, the weld was quenched by pouring a mixed solution of ice and water to freeze the microstructure. A large volume of eutectic structure was observed in the weld center of the stop action sample due to mutual diffusion of Al and Mg atoms induced by plastic deformation. During the sleeve retraction, a redistribution of eutectic structure and Mg alloy, and extensive diffusion led to an inhomogeneous intermetallic phase distribution in the Al top sheet.
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