Intended is to improve the corrosion resistance of an overlay used in a nuclear power plant, and to reduce dissolution of cobalt from an overlay. The corrosion and wear resistant overlay 7 is formed along a surface of a base 2 by laser lamination modeling, and is configured from a plurality of metal layers 1a, 1b, 1c, and 1d of a Co-base alloy. The thickness of carbide eutectics that precipitate in the metal layers 1a, 1b, 1c, and 1d is the largest in the metal layer 1a closest to the base 2, and is gradually smaller in the metal layers 1b, 1c, and 1d farther away from the base 2. The intensity of the laser beam applied to form layers by laser lamination modeling is adjusted so that the carbide eutectics that precipitate in at least the outermost metal layer 1d have a controlled size of 10 m or less.

An electrical steel strip friction stir welding method is provided that is able to inhibit the occurrence of coil joint fracture on a production line caused by degradation of mechanical properties and shape of the coil joint, under high work efficiency conditions. Double-sided friction stir welding with post-cooling is carried out under conditions so that the steel microstructures of the joined portion and the thermo-mechanically affected zone formed by joining become mainly ferrite phase, the conditions simultaneously satisfying the relationships of Expressions (1) to (4).