A precipitation hardening type soft magnetic ferritic stainless steel having an excellent machinability contains, in % by mass, C: 0.1% or less (excluding 0%), Si: 0.01 to 2.5%, Mn: 0.5% or less (excluding 0%), S: 0.1% or less (excluding 0%), Cr: 12.0 to 19.0%, Ni: 1.0 to 4.0%, Al: 0.5 to 3.0%, and at least one of Ti: 0.05 to less than 0.5% and Zr: 0.05 to less than 0.3%, as well as Bi: 0.02 to 0.5%, in which a remainder includes inevitable impurities and substantially is made of Fe, and the stainless steel has a structure substantially in a ferrite phase after solution annealing and aging, and a hardness of 300 Hv or higher after aging. The precipitation hardening type soft magnetic ferritic stainless steel is excellent in soft magnetic properties, age-hardenability, and corrosion resistance, as well as machinability.

Disclosed are aa austenitic stainless steel free of surface cracks and having excellent surface roughness in a bent portion and a manufacturing method thereof. The austenitic stainless steel according to an embodiment of the present disclosure includes, in percent by weight (wt %), 0.005 to 0.03% of C, 0.1 to 1% of Si, 0.1 to 2% of Mn, 6 to 12% of Ni, 16 to 20% of Cr, 0.01 to 0.2% of N, 0.25% or less of Nb, and the balance of Fe and inevitable impurities, wherein an average grain size (d) of a central portion in a thickness direction is 5 ?m or less, and a martensite area fraction measured in the bent portion after a 180? bending test is 10% or less.

Disclosed is a martensitic stainless steel with improved strength and corrosion resistance. The disclosed martensitic stainless steel sheet comprises, in percent by weight (wt %), 0.3 to 0.5% of C, 0.01 to 0.025% of N, 0.3 to 0.5% of Si, 0.4 to 0.6 of Mn, 13.1 to 14.5% of Cr, 0.95 to 1.10% of Mo, 0.05 to 0.3% of V, 0.3 to 0.5% of Ni, 0.001 to 0.5% of Cu, and the balance being Fe and inevitable impurities, and satisfies Formula (1). Formula (1): 16.4?(Cr+3.3Mo+16N)*(Mo+V)?23.3, wherein Cr, N, Mo, and V denote the contents (wt %) of respective elements.

Disclosed embodiments include fuel assemblies, fuel element, cladding material, methods of making a fuel element, and methods of using same.

Disclosed embodiments include fuel assemblies, fuel element, cladding material, methods of making a fuel element, and methods of using same.

The present invention relates to a method and system for treatment of a surface of a metallic material component, the method comprising the steps: electro-spark treating the surface of the metallic component by means of an electro-spark electrode, wherein the metallic material is a basically ferritic, perlitic and/or austenitic steel and the method creates a thin layer with martensitic microstructures at the surface of the metallic material component. Serpentines and quartz can be incorporated by an additional step as well as the surface randomly structured by this.

The present invention relates to a method and system for treatment of a surface of a metallic material component, the method comprising the steps: electro-spark treating the surface of the metallic component by means of an electro-spark electrode, wherein the metallic material is a basically ferritic, perlitic and/or austenitic steel and the method creates a thin layer with martensitic microstructures at the surface of the metallic material component. Serpentines and quartz can be incorporated by an additional step as well as the surface randomly structured by this.

A seamless steel pipe having a specific chemical composition. A ratio of Ti to N is in a range of 2.0 to 5.0. The steel pipe has a microstructure including tempered martensite having a volume ratio of 95% or more, and prior austenite grains having a grain size number of 8.5 or more. In a cross-section perpendicular to a rolling direction of the steel pipe a number of nitride-based inclusions having a particle size of 4 um or more is 100 or less per 100 mm.sup.2, a number of nitride-based inclusions having a particle size of less than 4 ?m is 1000 or less per 100 mm.sup.2, a number of oxide-based inclusions having a particle size of 4 ?m or more is 40 or less per 100 mm.sup.2, and a number of oxide-based inclusions having a particle size of less than 4 ?m is 400 or less per 100 mm.sup.2.

A seamless steel pipe having a specific chemical composition. A ratio of Ti to N is in a range of 2.0 to 5.0. The steel pipe has a microstructure including tempered martensite having a volume ratio of 95% or more, and prior austenite grains having a grain size number of 8.5 or more. In a cross-section perpendicular to a rolling direction of the steel pipe a number of nitride-based inclusions having a particle size of 4 um or more is 100 or less per 100 mm.sup.2, a number of nitride-based inclusions having a particle size of less than 4 ?m is 1000 or less per 100 mm.sup.2, a number of oxide-based inclusions having a particle size of 4 ?m or more is 40 or less per 100 mm.sup.2, and a number of oxide-based inclusions having a particle size of less than 4 ?m is 400 or less per 100 mm.sup.2.

This high strength hot rolled steel sheet has a predetermined chemical composition, in which the structure of the high strength hot rolled steel sheet contains martensite in an area ratio of 20% or more and 60% or less and ferrite in an area ratio of 40% or more, and the total area ratio of the martensite and the ferrite is 90% or more, the average grain size of the martensite is 5.0 m or more and 50 m or less, the ratio of the hardness of the martensite to the hardness of the ferrite is 0.6 or more and 1.6 or less, and the tensile strength of the high strength hot rolled steel sheet is 980 MPa or more.