Hot press-formed item manufacturing method, press-formed item, die, and die set
AssigneeNippon Steel Corporation
InventorsMasahiro Kubo, Naruhiko Nomura, Toshiya Suzuki
Life of this patent
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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.
Claims11
A method of producing a hot press-formed product, the method comprising:
- placing a hot-dip galvannealed steel sheet, comprising a hot-dip galvannealed layer, on a die so as to block a die hole of the die, and
- hot press-forming the hot-dip galvannealed steel sheet using the die,
- wherein the die comprises a hard layer having a skewness (Rsk), as measured in a direction from an outside of the 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 an entirety of a region of a steel sheet contact surface that is adjacent to a die shoulder portion, the steel sheet contact surface being located outside of the die hole and being configured to contact the hot-dip galvannealed steel sheet that is to be subjected to the hot press forming;
- and
- wherein the hard layer comprises a nitride steel layer as an outermost layer, and the nitride steel layer is a nitrided layer of a base material of the die, wherein the base material of the die is a steel.
A die, comprising a hard layer having a skewness (Rsk), as measured in a direction from an 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 an entirety of a region of a die shoulder adjacent surface that is adjacent to a die shoulder portion, the die shoulder adjacent surface being located outside of the die hole and adjacent to the die shoulder portion;
- and
- wherein the hard layer comprises a nitride steel layer as an outermost layer, and the nitride steel layer is a nitrided layer of a base material of the die, wherein the base material of the die is a steel.
Dependencies are inferred from the claim text.