# US 2021/0340643 A1 · Hot-press molding method and hot-press molded product > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0340643 A1 - Document ID: US20210340643A1 - Status: Published application - Kind: A1 - Application number: 17/378,898 - Filed: 2021-07-19 - Published: 2021-11-04 - Earliest claimed: 2016-11-14 - Assignees: Toyota Jidosha Kabushiki Kaisha - Applicants: Toyota Jidosha Kabushiki Kaisha - Inventors: Eiichi OTA; Yasuhiro Yogo; Tomoaki Ihara - Web page: https://patentgrep.com/patent/US20210340643A1 ## CPC - C21D 9/48: deep-drawing sheets - B21D 22/022: {by heating the blank or stamping associated with heat treatment (C21D takes precedence)} - B21D 22/208: {by heating the blank or deep-drawing associated with heat treatment (C21D takes precedence)} - C21D 1/22: Martempering - C21D 1/673: for die quenching - C21D 7/13: by hot working - C21D 8/00: Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) - C22C 38/04: containing manganese - C22C 38/18: containing chromium - C22C 38/38: with more than 1.5% by weight of manganese - C21D 9/00: Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor - C21D 9/46: for sheet metals - C21D 2211/001: Austenite - C21D 2211/002: Bainite - C21D 2211/005: Ferrite - C21D 2211/008: Martensite - C21D 2211/009: Pearlite - C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B) - B21D: WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL (working or processing of wire B21F) - C22C: ALLOYS (treatment of alloys C21D, C22F) ## Abstract 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. ## Claims ### Claim 1 A hot-press molding method comprising: 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, wherein 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, and wherein the second heating process is a process in which the first region and the second region are set to be lower than an austenite transformation start temperature, and the second region is transformed into ferrite, pearlite, or bainite. ### Claim 2 (depends on 1) The hot-press molding method according to claim 1, wherein, in the second heating process, a heating time from when heating starts until heating is completed is 1 to 12 minutes. ### Claim 3 A hot-press molded product comprising a first region having tempered martensite and a second region having martensite. ### Claim 4 (depends on 3) The hot-press molded product according to claim 3, wherein a hard to soft ratio which is a ratio of a maximum hardness to a minimum hardness in areas of the first region and the second region is 1.3 or more. ### Claim 5 (depends on 3) The hot-press molded product according to claim 3, wherein a hardness difference which is a difference between a maximum hardness and a minimum hardness in areas of the first region and the second region is 100 HV or more. ### Claim 6 (depends on 3) The hot-press molded product according to claim 3, wherein the tempered martensite is sorbite or troostite. ### Claim 7 (depends on 3) The hot-press molded product according to claim 3, wherein the hot-press molded product is a steel plate containing 0.1 to 0.6% carbon, and at least of 0.5 to 3% manganese and 0.05 to 3% chromium when the entire hot-press molded product is set to 100 mass %. ### Claim 8 A hot-press molded product comprising a first region having tempered martensite and a second region having at least one of ferrite, pearlite, and bainite. ### Claim 9 (depends on 8) The hot-press molded product according to claim 8, wherein a hard to soft ratio which is a ratio of a maximum hardness to a minimum hardness in areas of the first region and the second region is 1.3 or more. ### Claim 10 (depends on 8) The hot-press molded product according to claim 8, wherein a hardness difference which is a difference between a maximum hardness and a minimum hardness in areas of the first region and the second region is 100 HV or more. ### Claim 11 (depends on 8) The hot-press molded product according to claim 8, wherein the tempered martensite is sorbite or troostite. ### Claim 12 (depends on 8) The hot-press molded product according to claim 8, wherein the hot-press molded product is a steel plate containing 0.1 to 0.6% carbon, and at least of 0.5 to 3% manganese and 0.05 to 3% chromium when the entire hot-press molded product is set to 100 mass %.