# US 11,897,014 B2 · Hot press-formed part, and manufacturing method thereof

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- Number: US 11,897,014 B2
- Document ID: US11897014B2
- Status: Granted
- Kind: B2
- Application number: 18/096,260
- Filed: 2023-01-12
- Published: 2023-06-01
- Granted: 2024-02-13
- Earliest claimed: 2018-11-30
- Assignees: Posco
- Applicants: Posco Co., Ltd
- Inventors: Seong-Woo Kim; Jin-Keun Oh; Sang-Heon Kim; Hyo-Sik Chun
- Web page: https://patentgrep.com/patent/US11897014B2

## CPC

- B21D 35/007: {Layered blanks (B21D22/203 takes precedence; joining superposed plates B21D39/031, B21D39/034, B21D39/035)}
- B32B 15/012: {one layer being formed of an iron alloy or steel, another layer being formed of aluminium or an aluminium alloy}
- C21D 1/26: Methods of annealing
- C21D 1/673: for die quenching
- C21D 6/002: {containing Cr (C21D6/004 takes precedence)}
- C21D 6/005: {containing Mn}
- C21D 6/008: {containing Si}
- 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)
- C21D 8/0252: {with application of tension}
- C21D 8/0447: {characterised by the heat treatment}
- C21D 9/0068: {for particular articles not mentioned below}
- C21D 9/46: for sheet metals
- C21D 9/48: deep-drawing sheets
- C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/18: containing chromium
- C22C 38/28: with titanium or zirconium
- C22C 38/32: with boron
- C23C 2/12: Aluminium or alloys based thereon
- C23C 2/26: After-treatment (C23C2/14 takes precedence)
- C23C 2/28: Thermal after-treatment, e.g. treatment in oil bath
- C23C 2/29: {Cooling or quenching}
- C23C 2/40: Plates; Strips
- C23C 28/02: only coatings {only including layers} of metallic material
- C23C 28/021: {including at least one metal alloy layer}
- C23C 28/023: {only coatings of metal elements only}
- B21D 22/022: {by heating the blank or stamping associated with heat treatment (C21D takes precedence)}
- B21D 35/005: {characterized by the material of the blank or the workpiece (B21D26/053 takes precedence)}
- 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)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- 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)
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)

## Abstract

The present disclosure provides a hot-press formed part comprising a plated steel sheet and an aluminum alloy plated layer formed on the plated steel sheet, wherein the aluminum alloy plated layer comprises: an alloying layer (I) formed on the plated steel sheet and containing, by weight %, 5-30% of Al; an alloying layer (II) formed on the alloying layer (I) and containing, by weight %, 30 to 60% of Al; an alloying layer (III) formed on the alloying layer (II) and containing, by weight %, 20-50% of Al and 5-20% of Si; and an alloying layer (IV) formed continuously or discontinuously on at least a part of the surface of the alloying layer (III), and containing 30-60% of Al, wherein the rate of the alloying layer (III) exposed on the outermost surface of the aluminum alloy plated layer is 10% or more.

## Claims

### Claim 1

A method of manufacturing a hot-press formed member, the method comprising:
aluminum-plating a surface of a base steel sheet and coiling the steel sheet, thereby obtaining an aluminum-plated steel sheet;
annealing the aluminum-plated steel sheet, thereby obtaining an aluminum-iron alloy-plated steel sheet; and
hot-press forming the aluminum-iron alloy plated steel sheet,
wherein an aluminum plating amount is 30-200 g/m2 based on a single side surface of the steel sheet,
wherein a cooling rate to 250° C. is less than 20° C./sec after the aluminum plating,
wherein coiling tension is 0.5-5 kg/mm2 during the coiling,
wherein the annealing is performed in a batch annealing furnace in a heating temperature range of 550-750° C. for 30 minutes-50 hours,
wherein, when the heating is performed from room temperature to the heating temperature during the annealing, an average temperature increase rate is 10-100° C./h, and an average temperature increase rate in a 400-500° C. range is 1-15° C./h,
wherein a difference between an atmosphere temperature in the batch annealing furnace and a temperature of the steel sheet is determined to be 5-80° C., and
wherein a heat treatment is performed in a temperature range of Ac3-950° C. during the hot-press forming, the heating is performed at a temperature increase rate of 3-18° C./s to a temperature range from 200° C. to Ac3-950° C., and a heat treatment is performed for 1-15 minutes as a total heating time, where the total heating time is defined as the heating time including both the heating time in the temperature increase range and the heating time in the temperature range of Ac3-950° C., and hot-press forming is performed.

### Claim 2 (depends on 1)

The method of claim 1, wherein an average abrasion depth of 10 points of a hot-press forming die is 15 μm or less when the hot-press formed member is produced 500 times by the method of manufacturing the hot-press formed member as in claim 1.