Effects of Tool Geometry on Hardened Layer of Friction Stir Processed Cast Iron

In a previous study, the authors clarified that various cast irons can be hardened by friction stir processing (FSP). However, it was found that tool load must be set very high to obtain hardened layers with sufficient depth and area. In this study, the effects of tool geometry on the applied tool load were investigated to reduce the tool load required for forming hardened layers by FSP. As a result, it was found that the applied tool load can be reduced by 36% using a concave tool.