Provided are: a method for producing a high-speed tool steel material capable of increasing carbides in the structure of a high-speed tool steel product; a method for producing a high-speed tool steel product; and a high-speed tool steel product. The method for producing a high-speed tool steel material is provided with: a casting step for casting molten steel to obtain a steel ingot; a blooming step for heating the steel ingot obtained in said casting step to a temperature higher than 1120 C. and thereafter hot-working same to obtain an intermediate material; and a finishing step for heating the intermediate material obtained in the blooming step to a temperature of 900-1120 C. and thereafter hot-working same to obtain the high-speed tool steel material. Further, said method for producing a high-speed tool steel material is provided with an annealing step for annealing the high-speed tool steel material obtained in said finishing step. The present invention is also: a method for producing a high-speed tool steel product, wherein quenching and annealing is performed on the high-speed tool steel material obtained in the production method above; and a high-speed tool steel product.

Provided are: a method for producing a high-speed tool steel material capable of increasing carbides in the structure of a high-speed tool steel product; a method for producing a high-speed tool steel product; and a high-speed tool steel product. The method for producing a high-speed tool steel material is provided with: a casting step for casting molten steel to obtain a steel ingot; a blooming step for heating the steel ingot obtained in said casting step to a temperature higher than 1120 C. and thereafter hot-working same to obtain an intermediate material; and a finishing step for heating the intermediate material obtained in the blooming step to a temperature of 900-1120 C. and thereafter hot-working same to obtain the high-speed tool steel material. Further, said method for producing a high-speed tool steel material is provided with an annealing step for annealing the high-speed tool steel material obtained in said finishing step. The present invention is also: a method for producing a high-speed tool steel product, wherein quenching and annealing is performed on the high-speed tool steel material obtained in the production method above; and a high-speed tool steel product.

The invention relates to a stainless steel. The stainless steel consists of in weight % (wt. %):

TABLE-US-00001 C 0.32-0.50 Si 0.1-1.0 Mn 0.1-0.8 Cr11-14 Mo 1.8-2.6 V 0.35-0.70 N 0.05-0.19 optional elements, balance Fe and impurities.

The invention relates to a stainless steel. The stainless steel consists of in weight % (wt. %):

TABLE-US-00001 C 0.32-0.50 Si 0.1-1.0 Mn 0.1-0.8 Cr11-14 Mo 1.8-2.6 V 0.35-0.70 N 0.05-0.19 optional elements, balance Fe and impurities.

Provided are a steel sheet with excellent weldability, and a production method therefor. The steel sheet is characterized by having a specific composition and a metallographic structure containing, in terms of an area ratio, ferrite of 25% or more and 65% or less, martensite having iron-based carbides precipitated in the grains of 35% or more and 75% or less, and the balance structure other than the ferrite and the martensite of 20% or less (including 0%) in total, the average grain diameters of the ferrite and the martensite being respectively 5 m or lower, the total of concentration of Si and Mn at interface between the ferrite and the martensite being, in terms of an atomic concentration, 5% or more, and having a tensile strength of 900 MPa or higher.

Provided are a steel sheet with excellent weldability, and a production method therefor. The steel sheet is characterized by having a specific composition and a metallographic structure containing, in terms of an area ratio, ferrite of 25% or more and 65% or less, martensite having iron-based carbides precipitated in the grains of 35% or more and 75% or less, and the balance structure other than the ferrite and the martensite of 20% or less (including 0%) in total, the average grain diameters of the ferrite and the martensite being respectively 5 m or lower, the total of concentration of Si and Mn at interface between the ferrite and the martensite being, in terms of an atomic concentration, 5% or more, and having a tensile strength of 900 MPa or higher.

The steel material for a carburized bearing part according to the present invention contains, by mass %, C: 0.25 to 0.45%, Si: 0.15 to 0.45%, Mn: 0.40 to 1.50%, P: 0.015% or less, S: 0.005% or less, Cr: 0.60 to 2.00%, Mo: 0.10 to 0.35%, V: 0.20 to 0.40%, Al: 0.005 to 0.100%, Ca: 0.0002 to 0.0010%, N: 0.0300% or less and O: 0.0015% or less, with the balance being Fe and impurities, and satisfies Formulae (1) to (3).

1.20<0.4Cr+0.4Mo+4.5V<2.75(1)

A1/A2>0.50(2)

2.7C+0.4Si+Mn+0.45Ni+0.8Cr+Mo+V>2.55(3)

Formula (2) shows an area fraction of sulfides containing Ca in an amount of 1 mol % or more among sulfides having an equivalent circular diameter of 1 m or more.

A rolled steel sheet, for press hardening is provided, having a chemical composition where Ti/N>3.42, and the carbon, manganese, chromium and silicon contents satisfy:

[00001]$2.6.Math.C+\frac{\mathrm{Mn}}{5.3}+\frac{\mathrm{Cr}}{13}+\frac{\mathrm{Si}}{15}1.1.Math.\%.$

The sheet has a nickel content Ni.sub.surf at any point of the steel in the vicinity of the surface over a depth , such that: Ni.sub.surf >Ni.sub.nom, Ni.sub.nom denoting the nominal nickel content of the steel, and such that, Ni.sub.max denoting the maximum nickel content within :

[00002]$\frac{\left({\mathrm{Ni}}_{\max }+{\mathrm{Ni}}_{\mathrm{nom}}\right)}{2}\left(\right)0.6,$

and such that:

[00003]$\frac{\left({\mathrm{Ni}}_{\max }-{\mathrm{Ni}}_{\mathrm{nom}}\right)}{}0.01$

and the surface density of all of the particles D.sub.i and the surface density of the particles D.sub.(>2 m) larger than 2 micrometers satisfy, at least to a depth of 100 micrometers in the vicinity of the surface of said sheet:

D.sub.i+6.75 D.sub.(>2 m) <270

D.sub.i and D.sub.(>2 m) being expressed as number of particles per square millimeter, and said particles denoting all the oxides, sulfides, and nitrides, either pure or combined such as oxysulfides and carbonitrides, present in the steel matrix.

An iron-based alloy includes, in weight percent, carbon from about 1 to about 2 percent; manganese from about 0.1 to about 1 percent; silicon from about 0.1 to about 2.5 percent; chromium from about 11 to about 19 percent; nickel up to about 8 percent; vanadium from about 0.8 to about 5 percent; molybdenum from about 11 to about 19 percent; tungsten up to about 0.5 percent; niobium from about 1 to about 4 percent; cobalt up to about 5.5 percent; boron up to about 0.5 percent; nitrogen up to about 0.5 percent, copper up to about 1.5 percent, sulfur up to about 0.3 percent, phosphorus up to about 0.3 percent, up to about 5 percent total of tantalum, titanium, hafnium and zirconium; iron from about 50 to about 70 percent; and incidental impurities. The alloy is suitable for use in elevated temperature applications such as in valve seat inserts for combustion engines.

An iron-based alloy includes, in weight percent, carbon from about 1 to about 2 percent; manganese from about 0.1 to about 1 percent; silicon from about 0.1 to about 2.5 percent; chromium from about 11 to about 19 percent; nickel up to about 8 percent; vanadium from about 0.8 to about 5 percent; molybdenum from about 11 to about 19 percent; tungsten up to about 0.5 percent; niobium from about 1 to about 4 percent; cobalt up to about 5.5 percent; boron up to about 0.5 percent; nitrogen up to about 0.5 percent, copper up to about 1.5 percent, sulfur up to about 0.3 percent, phosphorus up to about 0.3 percent, up to about 5 percent total of tantalum, titanium, hafnium and zirconium; iron from about 50 to about 70 percent; and incidental impurities. The alloy is suitable for use in elevated temperature applications such as in valve seat inserts for combustion engines.