A method of producing a shaped structure support, e.g., for a vehicle, is disclosed. The method includes: heating a hollow workpiece of a steel material to a material transformation temperature range; deforming the hollow workpiece in a press into the shaped structure support having a predefined complex geometry while the hollow workpiece is in the material transformation temperature range; and quenching the hollow workpiece through contact with a press tool of the press to provide the shaped structure support with a martensitic microstructure.

A hot-press molding method of the present disclosure includes a first heating process in which a steel plate is heated and the entire steel plate becomes austenite, a first cooling process in which a cooling rate of the steel plate after the first heating process is partially changed, a first region which is a part of the steel plate is transformed into martensite, and a second region other than the first region remains as austenite, a second heating process in which the entire steel plate is reheated and the first region becomes tempered martensite, and a second cooling process in which the entire steel plate after the second heating process is cooled. At least one of the first cooling process and the second cooling process is performed during a molding process in which the steel plate is press-molded on a molding die.

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 μm or more and an aspect ratio of 2.5 or less is 4.0×10.sup.3 pieces/mm.sup.2 or less.

Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more, and excellent resistance to resistance welding cracking by properly adjusting its chemical composition and its microstructure such that a prior austenite average grain size is 7.5 μm or less, a volume fraction of martensite is 95% or more, and at least 10 Nb-based and Ti-based precipitates having a grain size of less than 0.10 μm are present on average per 100 μm.sup.2 of a cross section parallel to a thickness direction of the member within a range of 100 μm or less in the thickness direction from the surface of the member, and such that a B concentration in prior austenite grain boundaries is at least 3.0 times a B concentration at a position 5 nm away from the grain boundaries.

A method of producing a hot press-formed product, in which a die includes a hard layer having a skewness (Rsk), as measured in a direction from the outside of a die hole toward the inside of the die hole, of from −5.0 to 1.2, and a hardness Hv_Die of from HV 1,000 to 1,550, over the entirety of a region of a steel sheet contact surface that is adjacent to a die shoulder portion. The steel sheet contact surface is a surface located outside of the die hole and configured to contact a plated steel sheet (a plated steel sheet including at least one kind of plating layer selected from the group consisting of a hot-dip galvanizing layer and a zinc nickel plating layer) that is to be subjected to hot press forming.

A method for manufacturing a hot pressed product by heating a sheet material and quenching the sheet material while molding the sheet material includes a hole forming step of forming a pilot hole in the sheet material; a heating step of heating the sheet material in which the pilot hole is formed; and a molding step of forming a burred portion at the pilot hole by using a burring punch included in a die set while molding the sheet material in the die set. The pilot hole has an opening shape in which convex portions and concave portions are alternately arranged. A diameter of a circumscribed circle that is in contact with the convex portions is greater than a punch diameter of the burring punch. A diameter of an inscribed circle that is in contact with the concave portions is less than the punch diameter of the burring punch.

A method of producing a hot press-formed product, in which a die includes a hard layer having a skewness (Rsk), as measured in a direction from the outside of a die hole toward an inside of the die hole, of from −5.0 to 1.2, and a hardness Hv_Die of from HV 1,000 to 1,800, over the entirety of a region of a steel sheet contact surface that is adjacent to a die shoulder portion. The steel sheet contact surface is a surface located outside of the die hole and configured to contact a hot-dip galvannealed steel sheet that is to be subjected to hot press forming.

A system for producing components by hot forming includes a pre-heat station, a furnace, and a press. The pre-heat station is configured to receive a blank; and to pre-heat at least a portion of the blank to a pre-heat temperature by thermal conduction. The furnace is constructed and arranged to receive the pre-heated blank from the pre-heat station and to heat the entire blank to a deformation temperature. The deformation temperature is higher than the pre-heat temperature. The press is constructed and arranged to receive the heated blank from the furnace and to form the heated blank into the shape of the component.

The invention relates to a method for press hardening sheet steel components in which a blank is detached from a sheet steel band composed of a hardenable steel alloy and the blank is then austenitized, in that it is heated to a temperature greater than Ac.sub.3 and is then inserted into a forming tool and formed in the forming tool, and during the forming, is cooled at a speed greater than the critical hardening speed, characterized in that in order to inhibit microcracks of the second type from being produced during the forming and hardening process in the sheet metal blanks that are to be formed, oxygen is supplied adjacent to the positive radii and/or drawing edges; the invention also relates to a device for performing this method.

To solve the problem about the difference in temperature increasing rate between an overlapped part and a one-sheet part so as to further improve the corrosion resistance of plating after hot stamping. An overlapped blank for hot stamping includes: a first steel sheet; and at least one second steel sheet connected to a surface of the first steel sheet via a welding point and smaller in area than the first steel sheet, wherein: the first steel sheet is a plated steel sheet having an aluminum-based plated layer on both faces of the first steel sheet, and the second steel sheet is a plated steel sheet having an aluminum-based plated layer on both faces of the second steel sheet; a coating weight of the aluminum-based plated layer on the first steel sheet is W1 (g/m.sup.2) in terms of an average coating weight on both the faces; a coating weight of the aluminum-based plated layer on a surface on a side not in contact with the first steel sheet in the second steel sheet is W2 (g/m.sup.2); and each of the W1 and the W2 is within a range of 20 g/m.sup.2 or more and 120 g/m.sup.2 or less, and satisfies relationships of Expression (1) and Expression (2).