Abstract: A method of improving the functions of the surface of alloy steel by means of the irradiation of a laser beam is disclosed. In this method, the alloy steel is kept in contact with the aqueous solution of oxidizing acid or salt thereof and the irradiation of a laser beam is applied on the surface of the alloy steel through the aqueous solution, thereby concentrating an alloy component on the surface of the alloy steel. The aqueous solution contains at least one selected from the group consisting of nitric acid or nitrate, chromic acid or chromate, or permanganic acid or permanganate. In addition, the irradiation of the laser beam is applied so as to depict a given pattern on the surface, and a computer controls the shape and the size of the beam, the position of the alloy steel, and the like. The present method enables the improvement of a surface function of the alloy steel by providing various kinds of color-patterns.

Abstract: A method for improving corrosion resistance of bright annealed stainless steel is provided, in which the bright annealed stainless steel is subjected to alternating electrolysis in an aqueous nitric acid solution having a nitric acid concentration of 7 weight % or less in such a way that the stainless steel treated become an anode at least twice with the anode in the final run of electrolysis.