Abstract: 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.

Abstract: A panel-shaped formed product made of a metal sheet includes a top panel portion, an opening portion, and a vertical wall portion. The top panel portion is polygonal. The opening portion is provided in the top panel portion. The vertical wall portion extends from at least not less than two adjacent borders among the borders of the top panel portion. At least one pair of each vertical wall portion of pairs of adjacent vertical wall portions of the vertical wall portions has a stepped portion. As a result, the panel shaped formed product has fewer defects such as cracks and wrinkles even when it has a shape that is difficult to form.

Abstract: A panel-shaped formed product made of a metal sheet includes a top panel portion, an opening portion, and a vertical wall portion. The top panel portion is polygonal. The opening portion is provided in the top panel portion. The vertical wall portion extends from at least not less than two adjacent borders among the borders of the top panel portion. At least one pair of each vertical wall portion of pairs of adjacent vertical wall portions of the vertical wall portions has a stepped portion. As a result, the panel shaped formed product has fewer defects such as cracks and wrinkles even when it has a shape that is difficult to form.

Abstract: A hot press device according to the present disclosure includes a first press, a second press, a conveyance device linking the first press and the second press together, and a heating furnace provided within a conveyance range of the conveyance device.

Abstract: A hat member 1 includes a top-plate portion 13, first ridges 113, and two side walls 11. The two side walls have a middle hardness Dc of 300 HV or higher. Each of the two side walls 11 includes a softened portion L and a strength-transition portion T adjacent to the softened portion L. The softened portion L has a hardness Dn lower than the middle hardness Dc by at least 8% (Dc?Dn?0.08Dc). The strength-transition portion T extends 0.5 mm or longer from the softened portion L toward the first end of the side wall. The strength-transition portion T has a hardness Dt that transitionally changes within the range of 8% to 1% lower than the middle hardness Dc (0.92Dc?Dt?0.99Dc). The hat member 1 further includes two second ridges 114 and two flanges 14.

Abstract: A method of producing a press-formed product includes a steel plate heating step, a hot forging step and a hot stamping step. In the steel plate heating step, a steel plate is heated to 950° C. or more. In the hot forging step, the heated steel plate is forged to form a varying-thickness steel plate. In the hot stamping step, the heated varying-thickness steel plate is subjected to press-working by a press tooling to form a press-formed product, and the press-formed product that is formed is cooled inside the press tooling. Thus, a press-formed product that has high strength and for which a reduction in weight is possible can be produced.

Abstract: Provided is a coated steel sheet including a steel sheet, a first aluminum coating layer provided on a first surface of the steel sheet, a zinc compound layer or a metallic zinc layer provided on a surface of the first aluminum coating layer, and a second aluminum coating layer provided on a second surface of the steel sheet, as an outermost surface of the steel sheet. Further provided are a coated steel sheet coil using this coated steel sheet, and a method of producing a hot-press formed article, as well as an automobile part using a press formed article produced by the method of producing a hot-press formed article.

Abstract: A hat member 1 includes a top-plate portion 13, first ridges 113, and two side walls 11. The two side walls have a middle hardness Dc of 300 HV or higher. Each of the two side walls 11 includes a softened portion L and a strength-transition portion T adjacent to the softened portion L. The softened portion L has a hardness Dn lower than the middle hardness Dc by at least 8% (Dc?Dn?0.08Dc). The strength-transition portion T extends 0.5 mm or longer from the softened portion L toward the first end of the side wall. The strength-transition portion T has a hardness Dt that transitionally changes within the range of 8% to 1% lower than the middle hardness Dc (0.92Dc?Dt?0.99Dc). The hat member 1 further includes two second ridges 114 and two flanges 14.

Abstract: A hot press device according to the present disclosure includes a first press, a second press, a conveyance device linking the first press and the second press together, and a heating furnace provided within a conveyance range of the conveyance device.

Abstract: A steel sheet heating method that heats a steel sheet (K) to be pressed before hot press molding includes: bringing the steel sheet into a heating furnace (10) including a heater (15) on an inside surface of the heating furnace in a state where the steel sheet is supported in a vertical direction while an unnecessary portion of the steel sheet that becomes unnecessary after molding is fixedly supported by a support member (30); and performing heating at a prescribed temperature in the heating furnace, then taking the steel sheet out of the heating furnace, and after that cutting and removing the unnecessary portion before hot press molding or during hot press molding.

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 method of producing a press-formed product includes a steel plate heating step, a hot forging step and a hot stamping step. In the steel plate heating step, a steel plate is heated to 950° C. or more. In the hot forging step, the heated steel plate is forged to form a varying-thickness steel plate. In the hot stamping step, the heated varying-thickness steel plate is subjected to press-working by a press tooling to form a press-formed product, and the press-formed product that is formed is cooled inside the press tooling. Thus, a press-formed product that has high strength and for which a reduction in weight is possible can be produced.

Abstract: In hot press forming a thin steel sheet K, when cooling the thin steel sheet K by supplying a refrigerant to an ejection hole (27) communicated from a supply path (28) inside a lower mold (12), precooling in which an ejection amount per unit time period of the refrigerant from the ejection hole (27) is suppressed is carried out, and thereafter, main cooling is carried out by increasing the ejection amount per unit time period.

Abstract: A panel-shaped formed product made of a metal sheet includes a top panel portion, an opening portion, and a vertical wall portion. The top panel portion is polygonal. The opening portion is provided in the top panel portion. The vertical wall portion extends from at least not less than two adjacent borders among the borders of the top panel portion. At least one pair of each vertical wall portion of pairs of adjacent vertical wall portions of the vertical wall portions has a stepped portion. As a result, the panel shaped formed product has fewer defects such as cracks and wrinkles even when it has a shape that is difficult to form.

Abstract: A steel sheet heating method that heats a steel sheet (K) to be pressed before hot press molding includes: bringing the steel sheet into a heating furnace (10) including a heater (15) on an inside surface of the heating furnace in a state where the steel sheet is supported in a vertical direction while an unnecessary portion of the steel sheet that becomes unnecessary after molding is fixedly supported by a support member (30); and performing heating at a prescribed temperature in the heating furnace, then taking the steel sheet out of the heating furnace, and after that cutting and removing the unnecessary portion before hot press molding or during hot press molding.

Abstract: In hot press forming a thin steel sheet K, when cooling the thin steel sheet K by supplying a refrigerant to an ejection hole (27) communicated from a supply path (28) inside a lower mold (12), precooling in which an ejection amount per unit time period of the refrigerant from the ejection hole (27) is suppressed is carried out, and thereafter, main cooling is carried out by increasing the ejection amount per unit time period.

Abstract: Maximum allowable load values of a welded portion in respective fracture modes of a load fracture, a moment fracture, and a nugget interior fracture are found based on at least one of a sheet thickness t, a tensile strength TS, an elongation El, and a chemical composition of a nugget portion in each of spot-welded steel sheets, a nugget diameter d of a welded portion, an effective width B of the welded portion determined by a distance between adjacent welded portions, edges or ridge lines, and a sectional height H. Then, according to these fracture modes, an allowable load value at every moment after the maximum allowable load value of the welded portion is reached is found, and a displacement or a time at which the allowable load value becomes 0, that is, at which a complete fracture occurs is found, thereby finding a fracture limit.

Abstract: Maximum allowable load values of a welded portion in respective fracture modes of a load fracture, a moment fracture, and a nugget interior fracture are found based on at least one of a sheet thickness t, a tensile strength TS, an elongation El, and a chemical composition of a nugget portion in each of spot-welded steel sheets, a nugget diameter d of a welded portion, an effective width B of the welded portion determined by a distance between adjacent welded portions, edges or ridge lines, and a sectional height H. Then, according to these fracture modes, an allowable load value at every moment after the maximum allowable load value of the welded portion is reached is found, and a displacement or a time at which the allowable load value becomes 0, that is, at which a complete fracture occurs is found, thereby finding a fracture limit.

Abstract: According to exemplary embodiments of the present invention, a fracture prediction device for a spot welded portion can be provided. For example, the device may include an input arrangement configured to input all or some of a material strength, a plate thickness, a nugget diameter of a spot welding, a plate width of a joint, and a rotation angle of the joint in a tension test, based on a cross tension test and/or a shear tension test at a spot welded joint. The device can also include a first calculation arrangement configured to calculate a fracture strength parameter of the spot welded portion. A parameter storage arrangement may also be provided which can be configured to store the fracture strength parameter by each steel type. Further, the device may further have a second calculation arrangement configured to determine a fracture of the spot welded portion.

Abstract: According to exemplary embodiments of the present invention, a fracture prediction device for a spot welded portion can be provided. For example, the device may include an input arrangement configured to input all or some of a material strength, a plate thickness, a nugget diameter of a spot welding, a plate width of a joint, and a rotation angle of the joint in a tension test, based on a cross tension test and/or a shear tension test at a spot welded joint. The device can also include a first calculation arrangement configured to calculate a fracture strength parameter of the spot welded portion from all or any of the material strength, the plate thickness, the nugget diameter of the spot welding, the plate width of the joint, and the rotation angle of the joint in the tension test. A parameter storage arrangement may also be provided which can be configured to store the fracture strength parameter by each steel type.