STAINLESS STEEL EXCELLENT IN HIGH-TEMPERATURE CHLORIDE CORROSION RESISTANCE

摘要

PURPOSE:To easily and inexpensively obtain a stainless steel excellent in high- temp. chloride corrosion resistance by coating the surface of an austenitic stainless steel with Al and then subjecting the above to diffusion heat treatment in vacuum or in a nonoxidizing-gas atmosphere. CONSTITUTION:The surface of an austenitic stainless steel is coated with Al. It is preferable that the above Al coating is carried out by means of mechanical adhesion by an economical method free from the formation of intermetallic compounds, such as mechanical plating method and cold clad rolling method. Subsequently, diffusion heat treatment is applied to the above stainless steel in vacuum or in a nonoxidizing-gas atmosphere. It is preferable to carry out this heat treatment at about 800-1200 deg.C for about 1min-1hr. By the above heat treatment, the structure of the above steel in the vicinity of the surface is modified into a ferritic phase enriched in Al. It is further preferable to apply heating treatment to the above steel in an oxidizing atmosphere at about 600-1100 deg.C, by which a dense protective oxide layer is formed. By this method, the stainless steel excellent in high-temp. chloride corrosion resistance can be obtained.