Abstract
Aluminum alloy castings have been widely used for auto parts. However they suffer from some defects such as porosity, segregation and others. Fusion processes used to modify the surface locally, lead to secondary defects like porosity and cracking in modified zone. In this research, a new surface modification process, which utilizes FSW phenomenon, is developed for modifying the large and flat surface layer of cast aluminum alloy. It is named as Friction Thermomechanical Process (hereafter referred as FTMP). This one is categorized as solid-state process and required no additional filler materials. The coarse microstructure in as-cast alloy surface is continuously refined due to dynamic recrystallization during FTMP. Defects in the cast are eliminated in the surface zone of 2 mm in depth. Modification area is extremely extended by use of offset pined tool, resulting in enhanced stirring metals.
