Review of Friction Stir Processing (FSP) Parameters and Materials for Surface Composites

This paper presents a review of important aspects related to the Friction Stir Welding and Friction Stir Processing (FSW/FSP) concepts. The FSP, as a variation of the FSW, uses the same principle, but instead of the material joining, the FSP focuses on a surface modification aiming at improving surface properties of the substrate material. Thin surface composites can be made either by using grooves or drilled holes. FSP process parameters have been elaborated: axial force, rotational and traverse speed, tilt angle, insertion depth and tool geometry, as well as number of passes. Review of the used materials in fabrication of composites by using FSP is shortly presented. Effects of the FSP on mechanical properties have been discussed: effects on the microstructure, hardness and wear properties, tensile strength, and fracture and defects formation. FSP has evolved as an efficient method to modify surface structures, especially important for metallic materials that exposed to different harsh conditions, and further research will enable its wider use in industry.