Surface modification by novel friction thermomechanical process of aluminum alloy castings

This paper describes the surface modification process using friction phenomenon called friction thermomechanical process (hereafter referred to as FTMP). A non-consumable rod is forced to make contact with the substrate while rotating. The friction heat, generated at the interface between the rod and substrate, makes substrate metal plasticized. The coarse cast microstructures on the substrate surface have been continuously refined due to dynamic recrystallization. Surface modification was performed by FTMP to AC2B and AC4C aluminum alloy castings. The zone within 2-mm depth from surface was refined microstructures, disappeared cast defects and treated with hardness increment.