Abstract
A6063S-T5 is a material that is frequently used in construction materials, and in many cases, the surface of the material is coated with a composite coated films for durability and design purposes．However, if the composite coated films is interfered with as a foreign substance in the joint while the material is still coated, it may easily have an adverse effect on the joint strength． Therefore, it is usually necessary to remove the coated films before joining or to coat the part after joining．In this paper, the effect of composite coated films on the joining process of friction stir spot welding is clarified, and an efficient joining method for materials with composite coated films is proposed．It was shown that the effect of the composite coated films could be removed by using a triangular prism-shaped tool, and that the bonding area and strength could be controlled．
