Abstract: Disclosed is a structural austenitic stainless steel with superior proof stress and toughness at cryogenic temperatures. The steel has a composition essentially consisting of, by weight, not greater than 0.05% of carbon, 0.20 to 0.70% of nitrogen, not greater than 1.0% of silicon, not greater than 25% of manganese, 13 to 35% of chromium, 5 to 25% of nickel and the balance substantially iron. The chromium content and manganese content is selected to meet the condition of (Cr+0.9 Mn).gtoreq.20%. The index of cleanliness showing the amount of nonmetallic inclusions is not greater than 0.1%.

Abstract: A high-Al heat resistant steel comprising a base steel containing not more than 0.7% C, not more than 3.0% Si, not more than 2.0% Mn, 10 to 40% Ni, 9 to 30% Cr, 2 to 8% Al, with balance being Fe and unavoidable impurities, and an Al coating formed on the base steel. The Al coating diffuses into the base steel to form an intermediate Al alloyed layer during the Al coating or by heating after the coating, which alloyed layer prevents the Al coating from spalling, thus providing excellent resistance to oxidation, corrosion, carburization, nitrization and sulphurdization at elevated temperatures.

Abstract: In a continuous annealing furnace, a steel strip is conveyed by conventional hearth rolls made of heat-resistant cast steel, such as HK 40. However, since the formation of buildup is frequent, conventional hearth rolls are inappropriate for long-term operation of a continuous annealing furnace. In the hearth roll of the present invention, which consists of a solid or hollow roll body and a surface layer, the surface layer containing more than 15% by weight of Nb and the balance being inorganic material, the formation of buildup is not frequest, thereby making long-term operation of a continuous annealing furnace possible.