Abstract: To establish a method for obtaining a hot-press-formed steel member, which exhibits high strength, high tensile elongation (ductility) and high bendability, thereby having excellent deformation characteristics at the time of collision crush (crashworthiness), and which is capable of ensuring excellent delayed fracture resistance. A method for producing a hot-press-formed steel member by heating a steel sheet, which has a chemical component composition containing 0.10% (% by mass, and hereinafter the same shall apply) to 0.30% (inclusive) of C, 1.0% to 2.5% (inclusive) of Si, 1.0% to 3.0% (inclusive) of Si and Al in total and 1.5% to 3.0% (inclusive) of Mn, with the balance consisting of iron and unavoidable impurities, and hot press forming the steel sheet one or more times.

Abstract: In a method for obtaining a hot-press-formed steel member, a steel sheet containing 0.10-0.30 mass % of C, 1.0-2.5 mass % of Si, 1.0-3.0 mass % of Si and Al in total, and 1.5-3.0 mass % of Mn is heated at a heating temperature of not less than the Ac3 transformation point. The steel sheet is hot-press formed for one or more times. The starting temperature of the hot pressing is not more than the heating temperature but not less than the Ms point. The average cooling rate from (Ms point?150)° C. to 40° C. is 5° C./s or less. The hot-press-formed steel member has high strength, high tensile elongation, high bendability, excellent deformation characteristics at the time of collision crush, and excellent delayed fracture resistance.

Abstract: In one aspect of the present invention, a mechanical clinched joint component is a mechanical clinched joint component formed of two or more steel sheets, where the component includes at least one joint portion having a peel strength of 0.200 kN/mm or greater, and the component has a hardness of 360 Hv or greater. A method for manufacturing the component sequentially includes heating the two or more steel sheets to an Ac3 temperature or above, and performing mechanical clinch joining so that a carbon equivalent Ceq of the steel sheets, and a bottom-dead-center holding time t and a joining start temperature T during mechanical clinch joining satisfy relationships of equation (1) below and of equation (2) below: Ceq×(0.00209×t+0.000731×T?0.0365)?0.200 ??(1), and Ceq?0.00071×T+0.993 ??(2).

Abstract: Provided is a method for manufacturing a hot-press formed steel-member that is capable of reducing LME without causing cracking of a galvanized steel sheet. The method includes using a galvanized steel sheet, as a base steel, having a prescribed chemical composition, heating the galvanized steel sheet to not lower than an Ac3 transformation-point, and executing hot-press forming at least twice after the heating. Every hot-press forming in is executed so that to satisfy the following expression (1): (R/t)>?(a·(T?b)), where “R” is a curvature radius (mm) of a shoulder of a tool used in the hot-press forming, “t” is a thickness (mm) of the galvanized steel sheet, “T” is a forming-start temperature (° C.) of the hot-press forming, “a” is a constant 0.2984, and “b” is a constant 590.

Abstract: There is provided a method for manufacturing a hot-press formed steel-member, the method being capable of reducing LME without causing cracking of a galvanized steel sheet. The method includes a step of using a galvanized steel sheet, a base steel thereof, having a prescribed chemical composition, a heating step of heating the galvanized steel sheet to not lower than an Ac3 transformation-point, and a hot-press forming step of executing hot-press forming at least twice after the heating step. Furthermore, every hot-press forming in the hot-press forming step is executed in such a way as to satisfy the following expression (1) (R/t)>?(a·(T?b))??(1) where “R” is a curvature radius (mm) of a shoulder of a tool used in the hot-press forming, “t” is a thickness (mm) of the galvanized steel sheet, “T” is a forming-start temperature (° C.) of the hot-press forming, “a” is a constant 0.2984, and “b” is a constant 590.

Abstract: To establish a method for obtaining a hot-press-formed steel member, which exhibits high strength, high tensile elongation (ductility) and high bendability, thereby having excellent deformation characteristics at the time of collision crush (crashworthiness), and which is capable of ensuring excellent delayed fracture resistance. A method for producing a hot-press-formed steel member by heating a steel sheet, which has a chemical component composition containing 0.10% (% by mass, and hereinafter the same shall apply) to 0.30% (inclusive) of C, 1.0% to 2.5% (inclusive) of Si, 1.0% to 3.0% (inclusive) of Si and Al in total and 1.5% to 3.0% (inclusive) of Mn, with the balance consisting of iron and unavoidable impurities, and hot press forming the steel sheet one or more times.