A method for producing a machine component excellent in pitting resistance characteristics and toughness includes a carburizing step, performed on a steel material containing 0.13-0.30% C and 0.90-2.00% Cr in mass % and at least one of Si, Mn, Ni, Mo, Nb, V, Ti, B, Al, and N, balance Fe and unavoidable impurities; heating the material to 850-1030 C. to attain carbon concentration in a surface of 0.8-1.5%; cooling the material at an average rate of 5 C./sec or lower from a temperature higher than the A.sub.cm point of a surface layer to a cooling end temperature that is at least 50 C. lower than the A.sub.1 point to cause the surface layer to have a pearlite or bainite structure with dispersion; spheroidizing annealing at a temperature not higher than the A.sub.cm point at the surface layer; heating the material to not higher than the A.sub.cm point at the surface layer; and performing tempering.

A method for producing a surface-hardened material, comprising: an immersion step of immersing an iron steel material having nitrogen attached in the form of a solid solution on the surface thereof in a melt containing a chloride at a temperature ranging from 650 C. to 900 C.; and a cooling step of cooling the immersed iron steel material to a temperature equal to or lower than a martensitic transformation start temperature at a cooling rate equal to or higher than a lower critical cooling rare at which martensitic transformation starts.

[Object] To provide a steel sheet for carburizing having further improved formability and toughness after carburizing, and a method for manufacturing the same.

[Solution] A steel sheet consisting of, in mass %, C: more than or equal to 0.02%, and less than 0.30%, Si: more than or equal to 0.005%, and less than or equal to 0.5%, Mn: more than or equal to 0.01%, and less than or equal to 3.0%, P: less than or equal to 0.1%, S: less than or equal to 0.1%, sol. Al: more than or equal to 0.0002%, and less than or equal to 3.0%, N: more than or equal to 0.0001, and less than or equal to 0.035%, and the balance: Fe and impurities, in which average crystal grain size of ferrite is smaller than 10 m, average equivalent circle diameter of carbide is 5.0 m or smaller, percentage of number of carbides with an aspect ratio of 2.0 or smaller is 80% or larger relative to the total carbides, percentage of number of carbides present in ferrite crystal grain is 60% or larger relative to the total carbides, and average nitrogen concentration in a region ranging from topmost surface of steel sheet to a depth of 50 m is 0.040 mass % or higher and 0.200 mass % or lower.

A high-carbon cold rolled steel sheet having a specified chemical composition, and a method for manufacturing the same. The method includes forming a hot rolled steel sheet, performing cooling at an average cooling rate of 30 C./s or more and 70 C./s or less through a temperature range of a finish rolling end temperature to 660 C., coiling a hot rolled steel sheet at a temperature of 500 C. or more and 660 C. or less, and, optionally, pickling the coiled hot rolled steel sheet, and then performing a first box-annealing of holding at an annealing temperature in a temperature range of 650 to 720 C., then performing cold rolling at a rolling reduction ratio of 20 to 50%, and then performing a second box-annealing of holding at an annealing temperature in a temperature range of 650 to 720 C.

Disclosed is a method for manufacturing high-carbon bearing steel, which include: heating a billet at a temperature of about 950 to 1,050 C. for about 70 to 120 minutes, rolling the billet to manufacture a wire rod, winding the wire rod to manufacture a wire rod coil, cooling the wire rod coil, and subsequently heat treating the wire rod coil for spheroidizing and carbonitriding, respectively. The bearing steel may include an amount of about 0.9 to 1.3 wt % of carbon (C), an amount of about 1.1 to 1.6 wt % of silicon (Si), an amount of about 1.0 to 1.5 wt % of manganese (Mn), an amount of about 1.5 to 1.9 wt % of chromium (Cr), an amount of about 0.2 to 0.6 wt % of nickel (Ni), an amount of about 0.1 to 0.3 wt % of molybdenum (Mo), and the balance iron (Fe) based on the total weight thereof.

Disclosed is a method for manufacturing high-carbon bearing steel, which include: heating a billet at a temperature of about 950 to 1,050 C. for about 70 to 120 minutes, rolling the billet to manufacture a wire rod, winding the wire rod to manufacture a wire rod coil, cooling the wire rod coil, and subsequently heat treating the wire rod coil for spheroidizing and carbonitriding, respectively. The bearing steel may include an amount of about 0.9 to 1.3 wt % of carbon (C), an amount of about 1.1 to 1.6 wt % of silicon (Si), an amount of about 1.0 to 1.5 wt % of manganese (Mn), an amount of about 1.5 to 1.9 wt % of chromium (Cr), an amount of about 0.2 to 0.6 wt % of nickel (Ni), an amount of about 0.1 to 0.3 wt % of molybdenum (Mo), and the balance iron (Fe) based on the total weight thereof.

The present disclosure is directed at alloys and method for layer-by-layer deposition of metallic alloys on a substrate to produce a metallic part. Applications for the metallic parts include pumps, pump parts, valves, molds, bearings, cutting tools, filters or screens.

The present disclosure is directed at alloys and method for layer-by-layer deposition of metallic alloys on a substrate to produce a metallic part. Applications for the metallic parts include pumps, pump parts, valves, molds, bearings, cutting tools, filters or screens.

A matrix type hot work tool steel, in use, has an improved abrasive wear resistance in demanding applications. The steel is suited for applications in hot forging, die casting or hot extrusion. It is also suitable for press hardening, in particular for press hardening of Advance High Strength Steel (AHSS) and has a high hot wear resistance. The hot work tool steel has a composition including, in weight % (wt. %): C 0.65-0.85; Si 0.03-0.8; Mn 0.1-1.8; Cr 4.5-6.6; Mo 1.8-3.5; V 1.3-2.3; Al0.1; N0.12; Ni1; W0.5; Co2; Cu1; Nb0.1; Ti0.05; Zr0.05; Ta0.05; B0.01; Ca0.01; Mg0.01; REM0.2; and balance Fe and impurities.

A matrix type hot work tool steel, in use, has an improved abrasive wear resistance in demanding applications. The steel is suited for applications in hot forging, die casting or hot extrusion. It is also suitable for press hardening, in particular for press hardening of Advance High Strength Steel (AHSS) and has a high hot wear resistance. The hot work tool steel has a composition including, in weight % (wt. %): C 0.65-0.85; Si 0.03-0.8; Mn 0.1-1.8; Cr 4.5-6.6; Mo 1.8-3.5; V 1.3-2.3; Al0.1; N0.12; Ni1; W0.5; Co2; Cu1; Nb0.1; Ti0.05; Zr0.05; Ta0.05; B0.01; Ca0.01; Mg0.01; REM0.2; and balance Fe and impurities.