A steel sheet for a can having high strength, excellent ductility, and good corrosion resistance, and a method for manufacturing the steel sheet. The steel sheet has a chemical composition containing, by mass %, C: 0.020% or more and 0.130% or less, Si: 0.04% or less, Mn: 0.10% or more and 1.20% or less, P: 0.007% or more and 0.100% or less, S: 0.030% or less, Al: 0.001% or more and 0.100% or less, N: more than 0.0120% and 0.0200% or less, Nb: 0.0060% or more and 0.0300% or less, and Fe and inevitable impurities. An absolute value of a difference in an amount of solid solution Nb between a region from a surface to a position located at of a thickness and a region from a position located at of the thickness to a position located at 4/8 of the thickness is 0.0010 mass % or more.

A steel sheet for a can having high strength, excellent ductility, and good corrosion resistance, and a method for manufacturing the steel sheet. The steel sheet has a chemical composition containing, by mass %, C: 0.020% or more and 0.130% or less, Si: 0.04% or less, Mn: 0.10% or more and 1.20% or less, P: 0.007% or more and 0.100% or less, S: 0.030% or less, Al: 0.001% or more and 0.100% or less, N: more than 0.0120% and 0.0200% or less, Nb: 0.0060% or more and 0.0300% or less, and Fe and inevitable impurities. An absolute value of a difference in an amount of solid solution Nb between a region from a surface to a position located at of a thickness and a region from a position located at of the thickness to a position located at 4/8 of the thickness is 0.0010 mass % or more.

A clad material includes a first layer made of stainless steel and a second layer made of Cu or a Cu alloy and roll-bonded to the first layer. In the clad material, a grain size of the second layer measured by a comparison method of JIS H 0501 is 0.150 mm or less.

A clad material includes a first layer made of stainless steel and a second layer made of Cu or a Cu alloy and roll-bonded to the first layer. In the clad material, a grain size of the second layer measured by a comparison method of JIS H 0501 is 0.150 mm or less.

A bolt of the present invention is a high-strength bolt of high-carbon steel having a tempered martensite structure, wherein the composition of the bolt comprises: 0.50 mass % or more and 0.65 mass % or less of carbon (C); 1.5 mass % or more and 2.5 mass % or less of silicon (Si); 1.0 mass % or more and 2.0 mass % or less of chromium (Cr); 0.2 mass % or more and 1.0 mass % or less of manganese (Mn); and 1.5 mass % or more and 5.0 mass % or less of molybdenum (Mo); a total content of impurities being phosphor (P) and sulfur (S) is 0.03 mass % or more; and the remaining is iron (Fe). Furthermore, the carbon concentration satisfies the following Formula (1): 0.75X<1 . . . Formula (1) wherein, in Formula (1), X represents surface carbon concentration/inner carbon concentration. Therefore, the bolt of the present invention has low quench cracking susceptibility and excellent delayed fracture resistance, because an increase in temperature at which martensite transformation occurs (Ms point) on the surface side is held down.

[Object] To provide a steel sheet for carburizing that demonstrates improved extreme deformability prior to 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 0.5%, Mn: more than or equal to 0.01%, and less than 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: less than or equal to 0.2%, and the balance: Fe and impurities, in which average value of X-ray random intensity ratio, assignable to an orientation group of ferrite crystal grain ranging from {100}<011> to {223}<110>, is 7.0 or smaller, 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, and percentage of number of carbides present in the ferrite crystal grain is 60% or larger relative to the total carbides.

[Object] To provide a steel sheet for carburizing that demonstrates improved extreme deformability prior to 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 0.5%, Mn: more than or equal to 0.01%, and less than 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: less than or equal to 0.2%, and the balance: Fe and impurities, in which average value of X-ray random intensity ratio, assignable to an orientation group of ferrite crystal grain ranging from {100}<011> to {223}<110>, is 7.0 or smaller, 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, and percentage of number of carbides present in the ferrite crystal grain is 60% or larger relative to the total carbides.

A machine component includes a core made up of a steel for machine structural use, and a medium carbon-containing layer and a high carbon-containing layer formed of the steel for machine structural use, the medium carbon-containing layer covering the core, the high carbon-containing layer covering the medium carbon-containing layer and having a carbon concentration of 0.8-1.5%. The high carbon-containing layer is made up of a martensitic structure having carbides dispersed therein and a residual austenitic structure, wherein spheroidized carbides with an aspect ratio of 1.5 or less constitute 90% or more of a total number of the carbides, and the number of spheroidized carbides on prior austenite grain boundaries is 40% or less of the total number of the carbides.

A machine component includes a core made up of a steel for machine structural use, and a medium carbon-containing layer and a high carbon-containing layer formed of the steel for machine structural use, the medium carbon-containing layer covering the core, the high carbon-containing layer covering the medium carbon-containing layer and having a carbon concentration of 0.8-1.5%. The high carbon-containing layer is made up of a martensitic structure having carbides dispersed therein and a residual austenitic structure, wherein spheroidized carbides with an aspect ratio of 1.5 or less constitute 90% or more of a total number of the carbides, and the number of spheroidized carbides on prior austenite grain boundaries is 40% or less of the total number of the carbides.

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.