Abstract: A hot-stamping formed body includes: a steel sheet having a predetermined chemical composition; and a plating layer provided on a surface of the steel sheet, the plating layer having an adhesion amount of 10 g/m2 to 90 g/m2 and a Ni content of 10 mass % to 25 mass %, and containing a remainder consisting of Zn and impurities.

Abstract: The present invention has as its object the provision of a steel member and steel sheet having high tensile strength and toughness and excellent in hydrogen embrittlement resistance in a corrosive environment and methods for manufacturing the same. The steel member of the present invention has predetermined chemical constituents and has a maximum value of content of Cu in a range from the surface to a depth of 0 to 30 ?m of 1.4 times the content of Cu at a depth of 200 ?m.

Abstract: A steel sheet for hot stamping includes: a steel sheet having a predetermined chemical composition; and a plating layer provided on a surface of the steel sheet, the plating layer having an adhesion amount of 10 g/m2 to 90 g/m2 and a Ni content of 10 mass % to 25 mass %, and containing a remainder consisting of Zn and impurities. The steel sheet for hot stamping includes, in a surface layer region of the steel sheet, 80% or more by area % of grains having an average crystal orientation difference of 0.4° to 3.0° inside grains surrounded by grain boundaries having an average crystal orientation difference of 5° or more.

Abstract: The present invention has as its object the provision of a steel member and steel sheet having high tensile strength and toughness and excellent in hydrogen embrittlement resistance in a corrosive environment and methods for manufacturing the same. The steel member of the present invention has predetermined chemical constituents and has a maximum value of content of Cu in a range from the surface to a depth of 0 to 30 ?m of 1.4 times the content of Cu at a depth of 200 ?m.

Abstract: A hot stamped article of high strength steel sheet excellent in bending deformability having a predetermined chemical composition, having an area rate of 90% or more of the microstructures of the steel sheet comprised of one or more of lower bainite, martensite, and tempered martensite, and having a ratio of the length of grain boundaries with a rotational angle about a rotational axis of the <011> direction of the crystal grains of the lower bainite, martensite, and tempered martensite of 15° or more with respect to the length of grain boundaries with a rotational angle of 5° to 75° of 80% or more.

Abstract: A hot stamped article excellent in strength having a predetermined composition, having an average crystal grain size of prior austenite of 3 ?m or less, containing at least one of lower bainite, martensite, and tempered martensite in an area rate of 90% or more, and having a grain boundary solid solution ratio Z, defined by Z=(mass % of one or both of Nb and Mo at the grain boundaries)/(mass % of one or more of Nb and Mo at time of dissolution) of 0.3 or more.

Abstract: In a mold, at least one of a lower mold and an upper mold includes a coolant supply passage through which a liquid coolant is supplied to an inner space of a recess, and the mold includes an air escape passage through which air in the inner space of the recess is discharged upward.

Abstract: A steel member according to an aspect of the present invention has a predetermined chemical composition, in which a metallographic structure includes, by a volume %, 60.0% to 85.0% of martensite, 10.0% to 30.0% of bainite, 5.0% to 15.0% of residual austenite, and 0% to 4.0% of a remainder in microstructure. A length of a maximum minor axis of the residual austenite is 30 nm or longer. A number density of a carbide which exist in the steel member and has a circle equivalent diameter of 0.1 ?m or more and an aspect ratio of 2.5 or less is 4.0×103 pieces/mm2 or less.

Abstract: A method for manufacturing a quenched molding according to the present disclosure is a method including a first heat treatment process of heating a blanked steel material to a temperature higher than its Ac3 transformation point to perform austenite transformation, and then cooling to induce martensite transformation or bainite transformation, and a second heat treatment process of heating the steel material that has undergone the first heat treatment process to a temperature higher than the Ac3 transformation point to perform austenite transformation, and then cooling to induce martensite transformation. After the steel material has been heated to a temperature higher than the Ac3 transformation point in at least one process from out of the first heat treatment process or the second heat treatment process, molding is completed at a temperature higher than an Ar3 transformation point.

Abstract: A cooling method for a workpiece includes placing entirety of the workpiece in an inner space of a recess provided on a molding surface of a lower mold, pressing or restraining the workpiece by a mold including the lower mold and an upper mold in which a protrusion corresponding to the recess of the lower mold is provided on a molding surface, supplying a liquid coolant to the inner space of the recess through a coolant supply passage provided in at least one of the lower mold and the upper mold by a pump, and discharging air in the inner space of the recess upward through an air escape passage, and cooling the workpiece by immersing the entirety of the workpiece, which has been heated, in the liquid coolant that fills the recess.

Abstract: [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.

Abstract: A heat-treated steel sheet member having a chemical including, by mass %: C: 0.05 to 0.50%; Si: 0.50 to 5.0%; Mn: 1.5 to 4.0%; P: 0.05% or less; S: 0.05% or less; N: 0.01% or less; Ti: 0.01 to 0.10%; B: 0.0005 to 0.010%; Cr: optional amounts of Ni, Cu, Mo, V, Ca, Al, Nb, and REM, with the balance: Fe and impurities. The steel sheet member has a microstructure comprising: mainly martensite; and retained austenite of which a volume ratio is 5.0% or higher, a number density of retained carbide in the steel sheet member having circle-equivalent diameters of 0.1 mm or larger is 4.0×103/mm2 or lower, [(log fg0?log fg(0.02))/0.02<20.0] is satisfied when mechanical properties are measured using a sheet specimen specified in ASTM E8, a tensile strength is 1.4 GPa or higher, and a total elongation is 8.0% or higher.

Abstract: A steel sheet for hot stamping includes a steel structure represented by an area fraction of bainite, fresh martensite and tempered martensite: 80% or more in total, and a product of a number density (pieces/?m2) of carbides and a proportion of carbides precipitated into prior austenite grains in carbides: 0.50 or more.

Abstract: A steel sheet for hot stamping use used as a material for a hot stamped article excellent in strength or bending deformability, having a predetermined chemical composition, having a microstructure containing at least one of lower bainite, martensite, and tempered martensite in an area ratio of 90% or more, having an X-ray random intensity ratio of {112}<111> of the crystal grains forming the above lower bainite, martensite, or tempered martensite of 2.8 or more, having a number density of grain size 50 nm or less cementite or epsilon carbides in the microstructure of 1×1016/cm3 or more, and having a grain boundary solid solution ratio Z defined by Z=(mass % of one or both of Nb and Mo at grain boundaries)/(mass % of one or both of Nb and Mo at time of melting) of 0.4 or more.

Abstract: A hot stamped article excellent in strength having a predetermined composition, having an average crystal grain size of prior austenite of 3 ?m or less, containing at least one of lower bainite, martensite, and tempered martensite in an area rate of 90% or more, and having a grain boundary solid solution ratio Z, defined by Z=(mass % of one or both of Nb and Mo at the grain boundaries)/(mass % of one or more of Nb and Mo at time of dissolution) of 0.3 or more.

Abstract: [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.

Abstract: A hot stamped article having excellent shock absorption having a predetermined chemical composition, having a microstructure containing prior austenite having an average grain size of 3 ?m or less and further containing at least one of lower bainite, martensite, and tempered martensite in an area ratio of 90% or more, and having a grain boundary solid solution ratio Z defined by Z=(mass % of one or both of Nb and Mo at grain boundaries)/(mass % of one or both of Nb and Mo at time of melting) of 0.3 or more.

Abstract: A hot stamped article of high strength steel sheet excellent in bending deformability having a predetermined chemical composition, having an area rate of 90% or more of the microstructures of the steel sheet comprised of one or more of lower bainite, martensite, and tempered martensite, and having a ratio of the length of grain boundaries with a rotational angle about a rotational axis of the <011> direction of the crystal grains of the lower bainite, martensite, and tempered martensite of 15 or more with respect to the length of grain boundaries with a rotational angle of 5° to 75° of 80% or more.

Abstract: The present invention provides steel sheet excellent in cold formability and ductility after heat treatment and a method for production thereof. The steel sheet of the present invention is steel sheet which has a chemical composition containing, by mass %, C: 0.10 to 0.40%, Si: 0.30 to 1.00%, Mn: 0.30 to 1.00%, Al: 0.001 to 0.10%, P: 0.0001 to 0.02%, and S: 0.0001 to 0.01% and having a balance of Fe and impurities, which steel sheet characterized in that a ratio (B/A) of the number of carbides at the ferrite grain boundaries (B) to the number of carbides inside the ferrite grains (A) is over 1, a ferrite grain size is 5 ?m to 50 ?m, an average grain size of carbides is 0.4 ?m to 2.0 ?m, a pearlite area ratio is 6% or less, and a Vicker's hardness is 120 HV to 170 HV.

Abstract: A steel sheet for heat treatment having a chemical composition including, by mass %: C: 0.05 to 0.50%; Si: 0.50 to 5.0%; Mn; 1.5 to 4.0%; P: 0.05% or less; S: 0.05% or less; N: 0.01% or less; Ti: 0.01 to 0.10%; B: 0.0005 to 0.010%; Cr: 0 to 1.0%; Ni: 0 to 2.0%; Cu: 0 to 1.0%; Mo: 0 to 1.0%; V: 0 to 1.0%; Ca: 0 to 0.01%; Al: 0 to 1.0%; Nb: 0 to 1.0%; REM: 0 to 0.1%; and the balance: Fe and impurities, wherein a maximum height roughness Rz on a surface of the steel sheet is 3.0 to 10.0 ?m, and a number density of carbide being present in the steel sheet and having circle-equivalent diameters of 0.1 ?m or larger is 8.0×103/mm2 or lower.