Abstract: A ferrite-martensite dual-phase stainless steel has satisfactory corrosion resistance and workability for a material for the body of a freight car and excellent low-temperature toughness. The ferrite-martensite dual-phase stainless steel has a specified chemical composition, in which inequalities (I) and (II) below are satisfied, and a steel microstructure including a dual phase of a ferrite phase and a martensite phase, in which the content of the martensite phase is 5% or more and 95% or less in terms of vol. %: 10.5?Cr+1.5×Si?13.5??(I) 1.5?30×(C+N)+Ni+0.5×Mn?6.0??(II), where Cr and Si in inequality (I) above and C, N, Ni, and Mn in inequality (II) above respectively represent the contents (mass %) of the corresponding chemical elements.

Abstract: A ferrite-martensite dual-phase stainless steel has satisfactory corrosion resistance and workability for a material for the body of a freight car and excellent low-temperature toughness. The ferrite-martensite dual-phase stainless steel has a specified chemical composition, in which inequalities (I) and (II) below are satisfied, and a steel microstructure including a dual phase of a ferrite phase and a martensite phase, in which the content of the martensite phase is 5% or more and 95% or less in terms of vol. %: 10.5?Cr+1.5×Si?13.5??(I) 1.5?30×(C+N)+Ni+0.5×Mn?6.0??(II), where Cr and Si in inequality (I) above and C, N, Ni, and Mn in inequality (II) above respectively represent the contents (mass %) of the corresponding chemical elements.

Abstract: A flame spraying burner melts or partially melts with combustion heat, a spray material comprising a powdered fire-resisting material to thermally spray a damaged portion of a furnace wall or the like. The flame spraying burner includes a burner nozzle body having a central passage for supplying oxygen-contained gas, the central passage having a projecting leading end, and a plurality of fuel gas supply passages formed around the central passage. Each of the plurality of fuel gas supply passages has a leading end recessed from the leading end of the central passage. A cylindrical burner tile is positioned around the leading end of the fuel gas supply passages and extends to at least the leading end of the central passage. A plurality of oxygen jetting ports are formed in the radial direction around the leading end of the nozzle cap.

Abstract: An anti-oxidation agent for preventing oxidation of a stainless steel strip during continuous annealing comprising a colloidal inorganic substance which can be crystallized at a temperature not higher than 1300.degree. C. at least one compound having a melting point not higher than 1300.degree. C., selected from the group consisting of silicates, borates and phosphates, a dispersion agent, and the balance substantially water. The anti-oxidation agent is applied to the surface of the stainless steel strip. During the annealing, the anti-oxidation agent enhances the heat absorption so that the stainless steel strip temperature is elevated to the annealing temperature in a short time. The anti-oxidation agent on the strip surface forms a film of a fine structure which keeps the strip surface away from oxidizing components of the annealing atmosphere so as to suppress generation of oxide scale. The film is easily separated due to thermal contraction in the course of the cooling after the annealing.

Abstract: A descaling method for removing oxide scale from a hot-rolled stainless steel strip. A solution of an alkaline earth metal chloride is applied to the surface of the oxide scale layer formed on the hot-rolled stainless steel strip, and the solution is allowed to penetrate into the oxide scale layer. In a subsequent annealing, the solution is heated and dehydrated to become solid matter and the dehydrated matter is melted and diffused into the oxide scale layer to soften the oxide scale layer. The oxide scale layer is then removed by a simple mechanical descaling by, for example, grinding brushes with or without a subsequent chemical descaling by a weak acid solution.

Abstract: A method and apparatus for recovering blast furnace gas for utilizing in a power plant such as an electric power generator employs a plurality of cooling arrangements. The cooling arrangments includes a first arrangement located upstream of a dust-removal equipment for controlling temperature of blast furnace gas to be about or below a critical temperature of the dust-removal equipment. The cooling arrangments also include a second arrangement located downstream of the dust-removal equipment and upstream of a power generator turbine for controlling gas temperature to be about or below a critical temperature of the turbine. The first and second arrangements are operative independently of each other in response to gas temperature.