Abstract: A method of producing a mold steel, the method including a first process of preparing a molten steel A that is obtained after vacuum refining and has a component composition including from 0.005% to 0.1% by mass of C, from 1.0% to 5.0% by mass of Ni, from 3.0% to 8.0% by mass of Cr, more than 0% but less than or equal to 2.0% by mass of Mo, more than 0% but less than or equal to 3.5% by mass of Cu, and more than 0% but less than or equal to 2.0% by mass of Al, in which an amount of O is 0.005% by mass or less and an amount of N is 0.03% by mass or less; a second process of reducing the amount of O and the amount of N in the molten steel A, by slag refining the molten steel A, to obtain a molten steel B; and a third process of casting the molten steel B, is provided.

Abstract: A cold die steel excellent in the characteristic of suppressing dimensional change, which has a chemical composition in mass %: C: 0.7% or more and less than 1.6%, Si: 0.5 to 3.0%, Mn: 0.1 to 3.0%, P: less than 0.05% including 0%, S: 0.01 to 0.12%, Cr: 7.0 to 13.0%, one or two elements selected from the group consisting of Mo and W: amounts satisfying the formula (Mo+(W/2))=0.5 to 1.7%, V: less than 0.7% including 0, Ni: 0.3 to 1.5%, Cu: 0.1 to 1.0% and Al: 0.1 to 0.7%. Preferably, the die steel satisfies the formula in mass %: Ni/Al=1 to 3.7. It is preferred that the die steel also satisfies the following formula in mass %: (Cr?4.2×C)=5 or less and (Cr?6.3×C)=1.4 or more and that it contains 0.3% or less of Nb.

Abstract: Disclosed is a hot-working tool steel having improved toughness and high-temperature strength. Also disclosed is a method for producing the hot-working tool steel. The hot-working tool steel comprises the following components (by mass): C: 0.34-0.40%, Si: 0.3-0.5%, Mn: 0.45-0.75%, Ni: 0-0.5% (exclusive), Cr: 4.9-5.5%, (Mo+1/2W): 2.5-2.9% (provided that Mo and W are contained singly or in combination), and V: 0.5-0.7%, with the remainder being Fe and unavoidable impurities. Preferably, the cross-sectional structure of the hot-working tool steel upon quenching contains a granular structure and an acicular structure, wherein the granular structure (A %) accounts for 45 area % or less, the acicular structure (B %) accounts for 40 area % or less, and the remaining austenite (C %) accounts for 5 to 20 volume %.

Abstract: A cold die steel excellent in the characteristic of suppressing dimensional change, which has a chemical composition in mass %: C: 0.7% or more and less than 1.6%, Si: 0.5 to 3.0%, Mn: 0.1 to 3.0%, P: less than 0.05% including 0%, S: 0.01 to 0.12%, Cr: 7.0 to 13.0%, one or two elements selected from the group consisting of Mo and W: amounts satisfying the formula (Mo+(W/2))=0.5 to 1.7%, V: less than 0.7% including 0, Ni: 0.3 to 1.5%, Cu: 0.1 to 1.0% and Al: 0.1 to 0.7%. Preferably, the die steel satisfies the formula in mass %: Ni/Al=1 to 3.7. It is preferred that the die steel also satisfies the following formula in mass %: (Cr?4.2×C)=5 or less and (Cr?6.3×C)=1.4 or more and that it contains 0.3% or less of Nb.

Abstract: A cold die steel excellent in the characteristic of suppressing dimensional change, which has a chemical composition in mass %: C: 0.7% or more and less than 1.6%, Si: 0.5 to 3.0%, Mn: 0.1 to 3.0%, P: less than 0.05% including 0%, S: 0.01 to 0.12%, Cr: 7.0 to 13.0%, one or two elements selected from the group consisting of Mo and W: amounts satisfying the formula (Mo+(W/2))=0.5 to 1.7%, V: less than 0.7% including 0, Ni: 0.3 to 1.5%, Cu: 0.1 to 1.0% and Al: 0.1 to 0.7%. Preferably, the die steel satisfies the formula in mass %: Ni/Al=1 to 3.7. It is preferred that the die steel also satisfies the following formula in mass %: (Cr?4.2 ×C)=5 or less and (Cr?6.3×C)=1.4 or more and that it contains 0.3% or less of Nb.

Abstract: Provided is a razor blade material which has excellent high hardness, high strength and high corrosion resistance. The material is made of an Fe-base alloy containing, by mass %, not less than 0.5% carbon, 9.0 to 14.0% Cr and from more than zero to 8.0% Mo, wherein precipitates, which can be observed at an optional cross section of the razor blade material, have a diameter of less than 0.1 m. The alloy has preferably a chemical composition of 0.5 to 5.0% carbon, 9.0 to 14.0% Cr and 0.5 to 8.0% Mo, 0.5 to 8.0% of B+Si, and the balance of Fe and unavoidable impurities. Preferably, the alloy has a metal structure, not less than 30 volume % of which is amorphous. The material has a thickness of 30 to 100 &mgr;m. The razor blade is preferably coated with polytetrafluoroethylene (PTFE).

Abstract: There are provided a high-hardness prehardened steel for cold working having excellent machinability containing, by mass, not less than 0.3% but less than 0.5% C, 0.7 to 2.0% Si, and 0.08 to 0.25% S, a die for cold working which is fabricated by cutting this prehardened steel at a cutting speed not less than 50 m/min. This steel is hardened and tempered to have a hardness not less than 50 HRC. Preferably, this steel consists, by mass, not less than 0.3% but less than 0.5% C, 0.7 to 2.0% Si, 0.1 to 2.0% Mn, 0.08 to 0.25% S, 0.5 to 15.0% Cr, at least one selected from the group consisting of W and Mo an amount of which one is not more than 3.5% in total in terms of (Mo+1/2W), not more than 4.0% V, not more than 0.15% N, and the balance Fe and incidental impurities.

Abstract: Provided is a razor blade material has excellent high hardness, high strength and high corrosion resistance. The material is made of an Fe-base alloy containing, by mass %, 0.5 to 5.0% carbon, 9.0 to 14.0% Cr and 0.5 to 8.0% Mo. The material includes precipitates which can be observed at an optional sectional surface of the razor blade material and each of which has a diameter of less than 0.1 &mgr;m. The alloy has preferably a chemical composition of 0.5 to 5.0% carbon, 9.0 to 14.0% Cr and 0.5 to 8.0% Mo, 0.5 to 8.0% of B+Si, and the balance of Fe and unavoidable impurities. Preferably, the alloy material has a metal structure, not less than 30 volume % of which is amorphous. The material has a thickness of 30 to 100 &mgr;m. The material is preferably coated with polytetrafluoroethylene (PTFE).

Abstract: There are provided a high-hardness prehardened steel for cold working having excellent machinability containing, by mass, not less than 0.3% but less than 0.5% C, 0.7 to 2.0% Si, and 0.08 to 0.25% S, a die for cold working which is fabricated by cutting this prehardened steel at a cutting speed not less than 50 m/min. This steel is hardened and tempered to have a hardness not less than 50 HRC. Preferably, this steel consists, by mass, not less than 0.3% but less than 0.5% C, 0.7 to 2.0% Si, 0.1 to 2.0% Mn, 0.08 to 0.25% S, 0.5 to 15.0% Cr, at least one selected from the group consisting of W and Mo an amount of which one is not more than 3.5% in total in terms of (Mo+1/2W), not more than 4.0% V, not more than 0.15% N, and the balance Fe and incidental impurities.

Abstract: A high strength steel for dies has excellent machinability and including, by weight, 0.005 to 0.1% C, not more than 1.5% Si, not more than 2.0% Mn, from 3.0 to less than 8.0% Cr, not more than 4.0% Ni, 0.1 to 2.0% Al, not more than 3.5% Cu, and balance of Fe and unavoidable impurities including N and O, and which has a metal structure whose primary microstructure is martensite, wherein N and O as impurities are restricted to amount ranges of not more than 0.02% N and not more than 0.003% O. In the invention, an improvement in the machinability in heavy cutting an improvement in the precision electro discharge machining property and high-grade polishing property can be achieved when the above high strength steel has a chemical composition in which the value of (7.7×C (wt %))+(2.2×Si (wt %))+271.2×S (wt %)) is preferably not less than 2.5 and more preferably not more than 6.

Abstract: A high strength steel for dies has excellent machinability and consists essentially of, by weight, 0.005 to 0.1% C, not more than 1.5% Si, not more than 2.0% Mn, from 3.0 to less than 8.0% Cr, not more than 4.0% Ni, 0.1 to 2.0% Al, not more than 3.5% Cu, and balance of Fe and inevitable impurities including N and 0, and which has a metal structure whose primary microstructure is martensite, wherein N and 0 as impurities are restricted to amount ranges of not more than 0.02% N and not more than 0.003% 0.