Abstract: A steel which does not suffer from hydrogen embrittlement contains 0.3-30% of Cr as the base material, and has an oxide film having a thickness of 100 nm or more formed on its surface. The oxide film contains at least two elements selected among Fe, Cr and Al in the form of oxides, respectively in an amount of 5 atom % or more. The oxide film is formed through single-step or two-step heating wherein the steel is heated in the atmosphere at 600-900° C. for not less than 3 minutes but not more than 2 hours if necessary, and then heated in a hydrogen atmosphere at 700-1200° C. for not less than 3 minutes but not more than 2 hours while controlling the water vapor partial pressure within the range from 10?8 to 10?1 MPa. The steel is adapted for use in hydrogen gas environments, such as a container or other hardware.

Abstract: An austenitic stainless steel for use in a hydrogen gas atmosphere comprises, in mass %, C: 0.10% or less, Si: 1.0% or less, Mn: 0.01 to 30%, P: 0.040% or less, S: 0.01% or less, Cr: 15 to 30%, Ni: 5.0 to 30%, Al: 0.10% or less, N: 0.001 to 0.30 % with the balance Fe and inevitable impurities. An X-ray (111) integration intensity of a cross section along the direction rectangular to the working direction is five times that in a random direction or less, and the X-ray integration intensity ratio of a cross section along the working direction satisfies I(220)/I(111)?10. The high strength steel can also contain one or more of the groups of Mo and W; V, Nb, Ta, Ti, Zr and Hf; B; Cu and Co; Mg, Ca, La, Ce, Y, Sm, Pr and Nd.

Abstract: An austenitic stainless steel excellect in high temperature strength and creep rupture ducitility which comprises, on the percent by mass basis, C: 0.03-0.12%, Si: 0.2-2%, Mn: 0.1-3%, P: 0.03% or less, S: 0.01% or less, Ni: more than 18% and less than 25%, Cr: more than 22% and less than 30%, Co: 0.04-0.8%, Ti: 0.002% or more and less than 0.01%, Nb: 0.1-1%, V: 0.01-1%, B: more than 0.0005% and 0.2% or less, sol. Al: 0.0005% or more and less than 0.03%, N: 0.1-0.35% and O (Oxygen): 0.001-0.008%, with the balance being Fe and impurities. The austenitic stainless steel may contain a specified amount of one or more element(s) of Mo and W, and/or a specified amount of one or more element(s) of Mg, Zr, Ca, REM, Pd and Hf.

Abstract: A high-strength stainless steel, having good mechanical properties and corrosion resistance in a high-pressure hydrogen gas environment, and excellent in stress corrosion cracking resistance, and a container or other device for high-pressure hydrogen gas, which is made of the said stainless steel, are provided. The stainless steel is characterized in that it consists of, by mass %, C: not more than 0.02%, Si: not more than 1.0%, Mn: 3 to 30%, Cr: more than 22% but not more than 30%, Ni: 17 to 30%, V: 0.001 to 1.0%, N: 0.10 to 0.50% and Al: not more than 0.10%, and the balance Fe and impurities. Among the impurities, P is not more than 0.030%, S is not more than 0.005%, and Ti, Zr and Hf are not more than 0.01% respectively, and the contents of Cr, Mn and N satisfy the following relationship [1]: 5Cr+3.

Abstract: A high-strength stainless steel, having good mechanical properties and corrosion resistance in a high-pressure hydrogen gas environment, is used as a container or other device for high-pressure hydrogen gas, and consists of, by mass %, C: not more than 0.04%, Si: not more than 1.0%, Mn: 7 to 30%, Cr: 15 to 22%, Ni: 5 to 20%, V: 0.001 to 1.0%, N: 0.20 to 0.50% and Al: not more than 0.10%, and the balance Fe and impurities. Among the impurities, P is not more than 0.030%, S is not more than 0.005%, and Ti, Zr and Hf are not more than 0.01% respectively, and the contents of Cr, Mn and N satisfy the relationship, 2.5Cr+3.4Mn?300N. The weld metal of the welded joint of the container or other device made of the said stainless steel satisfies the relationship, ?11?Nieq?1.1×Creq??8.

Abstract: An austenitic stainless steel suited for ultra supercritical boilers, which consists of C: 0.03-0.12%, Si: 0.1-1%, Mn: 0.1-2%, Cr: not less than 20% but less than 28%, Ni: more than 35% but not more than 50%, W: 4-10%, Ti: 0.01-0.3%, Nb: 0.01-1%, sol. Al: 0.0005-0.04%, B: 0.0005-0.01%, and the balance Fe and impurities; and also characterized by the impurities whose contents are restricted to P: not more than 0.04%, S: not more than 0.010%, Mo: less than 0.5%, N: less than 0.02%, and O (oxygen): not more than 0.005%. Heat resistant pressurized parts excellent in thermal fatigue properties and structural stability at high temperatures, which have a coarse grain whose grain size number is 6 or less, and whose mixed grain ratio is 10% or less.

Abstract: An austenitic stainless steel excellent in high temperature strength, high temperature ductility and hot workability, consisting of, by mass %, C: more than 0.05% to 0.15%, Si: 2% or less, Mn: 0.1 to 3%, P: 0.04% or less, S: 0.01% or less, Cr: more than 20% to less than 28%, Ni: more than 15% to 55%, Cu: more than 2% to 6%, Nb: 0.1 to 0.8%, V: 0.02 to 1.5%, sol. Al: 0.001 to 0.1%, but sol.Al?0.4×N, N: more than 0.05% to 0.3% and O (Oxygen): 0.006% or less, but O?1/(60×Cu), and the balance Fe and impurities. The austenitic stainless steel may contain at least one of Co, Mo, W, Ti, B, Zr, Hf, Ta, Re, Ir, Pd, Pt and Ag, and/or at least one of Mg, Ca, Y, La, Ce, Nd and Sc.

Abstract: An austenitic stainless steel excellent in high temperature strength, high temperature ductility and hot workability, consisting of, by mass %, C: more than 0.05% to 0.15%, Si: 2% or less, Mn: 0.1 to 3%, P: 0.04% or less, S: 0.01% or less, Cr: more than 20% to less than 28%, Ni: more than 15% to 55%, Cu: more than 2% to 6%, Nb: 0.1 to 0.8%, V: 0.02 to 1.5%, sol. Al: 0.001 to 0.1%, but sol.Al≦0.4×N, N: more than 0.05% to 0.3% and O (Oxygen): 0.006% or less, but O≦1/(60×Cu), and the balance Fe and impurities. The austenitic stainless steel may contain at least one of Co, Mo, W, Ti, B, Zr, Hf, Ta, Re, Ir, Pd, Pt and Ag, and/or at least one of Mg, Ca, Y, La, Ce, Nd and Sc.

Abstract: An austenitic stainless steel which comprises, on the percent by mass basis, C: 0.03-0.12%, Si: 0.2 -2%, Mn: 0.1-3%, P: 0.03% or less, S: 0.01% or less, Ni: more than 18% and less than 25%, Cr: more than 22% and less than 30%, Co: 0.04-0.8%, Ti: 0.002% or more and less than 0.01%, Nb: 0.1-1%, V:0.01 -1%, B: more than 0.0005% and 0.2% or less, sol. Al: 0.0005% or more and less than 0.03%, N: 0.1-0.35% and 0 (Oxygen): 0.001-0.008%, with the balance being Fe and impurities can be utilized as materials such as steel tubes used as a superheater tube, reheater tube for a boiler and a furnace tube for the chemical industry, and a steel plate, a steel bar and a steel forging and the like, which are used as a heat resistant, pressure-tight member, whereby extremely large effects on the promotion of increasing high temperature and high pressure steam in a boiler for an electric power-generation can be obtained.

Abstract: An austenitic stainless steel suited for ultra supercritical boilers, which consists of C: 0.03-0.12%, Si: 0.1-1%, Mn: 0.1-2%, Cr: not less than 20% but less than 28%, Ni: more than 35% but not more than 50%, W: 4-10%, Ti: 0.01-0.3%, Nb: 0.01-1%, sol. Al: 0.0005-0.04%, B: 0.0005-0.01%, and the balance Fe and impurities; and also characterized by the impurities whose contents are restricted to P: not more than 0.04%, S: not more than 0.010%, Mo: less than 0.5%, N: less than 0.02%, and O (oxygen): not more than 0.005%.