| 摘要 |
PURPOSE:To make Cr-stainless steel of excellent mechanical characteristics simply and at lower cost by a means in which the surface of a Cr-stainless steel is applied with Ni-plating and then subjected to a heating treatment in order to promote the diffusion of Ni into the steel and to aid the formation of Fe-Ni-Cr alloy phase. CONSTITUTION:The surface of a ferrite or martensite series Cr-stainless steel, including low-Ni stainless steel, is applied with an approx. 5 to 10mu thickness of Ni plating, and then annealing or hardening treatment is made to accelerate the diffusion of Ni into the steel. The preferred temperature in this treatment is 750 to 1,100 deg.C, most preferably 900 to 1,000 deg.C, and also the preferred residence time in the furnace for the formation of Ni-diffusion layer is approx. 5min. Because the diffusion layer has a composition similar to an austenite stainless steel comprising Fe-Ni-Cr, the stainless steel has a corrosion resistance which is favorably comparable with the 18-8 stainless steel. Also, because all but the several micron portion of the surface is composed of Cr-stainless steel, the steel has excellent mechanical characteristics. |
