# US 11,027,522 B2 · Steel sheet for hot stamping

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- Number: US 11,027,522 B2
- Document ID: US11027522B2
- Status: Granted
- Kind: B2
- Application number: 16/467,295
- Filed: 2017-01-17
- Published: 2020-03-26
- Granted: 2021-06-08
- Earliest claimed: 2017-01-17
- Assignees: Nippon Steel Corporation
- Applicants: Nippon Steel Corporation
- Inventors: Genki Abukawa; Kunio Hayashi; Kazuo Hikida; Kaoru Kawasaki
- Web page: https://patentgrep.com/patent/US11027522B2

## CPC

- B32B 15/013: {one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium}
- C21D 6/04: Hardening by cooling below 0 degrees Celsius
- C21D 6/004: {containing Cr and Ni}
- C21D 6/005: {containing Mn}
- C21D 6/008: {containing Si}
- C21D 8/02: during manufacturing of plates or strips (C21D8/12 takes precedence)
- C21D 8/0236: {Cold rolling}
- C21D 8/04: to produce plates or strips for drawing, e.g. for deep-drawing
- C21D 8/0426: {Hot rolling}
- C21D 8/0436: {Cold rolling}
- C21D 8/0463: {following hot rolling}
- C21D 8/0473: {Final recrystallisation annealing}
- C21D 9/46: for sheet metals
- C21D 9/48: deep-drawing sheets
- C22C 38/001: {containing N}
- 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 38/12: containing tungsten, tantalum, molybdenum, vanadium, or niobium
- C22C 38/14: containing titanium or zirconium
- C22C 38/22: with molybdenum or tungsten
- C22C 38/26: with niobium or tantalum
- C22C 38/32: with boron
- C22C 38/38: with more than 1.5% by weight of manganese
- C22C 38/44: with molybdenum or tungsten
- C22C 38/48: with niobium or tantalum
- C22C 38/50: with titanium or zirconium
- C22C 38/54: with boron
- C22C 38/58: with more than 1.5% by weight of manganese
- C21D 2211/002: Bainite
- C21D 2211/004: Dispersions; Precipitations
- C21D 2211/008: Martensite
- 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)

## Abstract

A steel sheet for hot stamping includes a steel structure represented by an area fraction of bainite, fresh martensite and tempered martensite: 80% or more in total, and a product of a number density (pieces/μm2) of carbides and a proportion of carbides precipitated into prior austenite grains in carbides: 0.50 or more.

## Claims

### Claim 1

A steel sheet for hot stamping comprising
a steel structure comprising
an area fraction of bainite, fresh martensite and tempered martensite: 80% or more in total, and
a product of a number density of carbides, in pieces/μm2, and a proportion of carbides precipitated into prior austenite grains in carbides: 0.50 or more and 10 or less.

### Claim 2 (depends on 1)

The steel sheet for hot stamping according to claim 1, wherein a C content is not less than 0.27 mass % nor more than 0.60 mass %.

### Claim 3 (depends on 1)

The steel sheet for hot stamping according to claim 1, wherein a Vickers hardness is 500 Hv or more.

### Claim 4 (depends on 2)

The steel sheet for hot stamping according to claim 2, wherein a Vickers hardness is 500 Hv or more.

### Claim 5 (depends on 1)

The steel sheet for hot stamping according to claim 1, comprising a plating layer.

### Claim 6 (depends on 2)

The steel sheet for hot stamping according to claim 2, comprising a plating layer.

### Claim 7 (depends on 3)

The steel sheet for hot stamping according to claim 3, comprising a plating layer.

### Claim 8 (depends on 4)

The steel sheet for hot stamping according to claim 4, comprising a plating layer.