Experimental Investigation of Raster Tool Path Strategy for Friction Stir Processing of Magnesium Alloy

Friction stir processing is an emerging method for refining the grain structure of the metals. Single pass friction stir processing of magnesium alloys has been reported in the literature, and very few works address the multi-pass friction stir processing. However, most of the studies are limited to a very small region and do not show the properties of complete processed blank. In the present work, a raster tool path strategy is adopted to modify the microstructure of the as-cast magnesium alloy. The tool rotation direction and tool shoulder overlap are varied to process the magnesium samples. The microstructural evolution of the processed samples is investigated. Experimental observations show that raster scan parameters significantly affect the microstructural variation within each sample and across the samples. Based on the findings, a raster tool path strategy is proposed for grain refinement without any defect in the processed region.