# US 9,040,169 B2 · Hot-dip galvanized steel sheet and alloyed hot-dip galvanized steel sheet, each having excellent workability, high yield ratio and high strength

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- Number: US 9,040,169 B2
- Document ID: US9040169B2
- Status: Granted
- Kind: B2
- Application number: 13/635,768
- Filed: 2011-03-30
- Published: 2013-01-17
- Granted: 2015-05-26
- Earliest claimed: 2010-03-31
- Assignees: Kobe Steel, Ltd.
- Applicants: Kazuyuki Hamada; Tatsuya Asai
- Inventors: Kazuyuki Hamada; Tatsuya Asai
- Web page: https://patentgrep.com/patent/US9040169B2

## CPC

- C22C 38/06: containing aluminium
- C21D 8/0236: {Cold rolling}
- C21D 8/0273: {Final recrystallisation annealing}
- C21D 8/0473: {Final recrystallisation annealing}
- C21D 9/46: for sheet metals
- C21D 9/48: deep-drawing sheets
- C22C 38/001: {containing N}
- C22C 38/04: containing manganese
- C22C 38/22: with molybdenum or tungsten
- C22C 38/28: with titanium or zirconium
- C22C 38/38: with more than 1.5% by weight of manganese
- C23C 2/06: Zinc or cadmium or alloys based thereon
- C23C 2/28: Thermal after-treatment, e.g. treatment in oil bath
- C23C 2/29: {Cooling or quenching}
- C21D 8/0426: {Hot rolling}
- C21D 8/0436: {Cold rolling}
- C21D 8/0463: {following hot rolling}
- C21D 2211/002: Bainite
- C21D 2211/005: Ferrite
- C21D 2211/008: Martensite
- Y10T 428/12799: Next to Fe-base component [e.g., galvanized]
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- 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)
- 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)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Disclosed is a hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet, which has a tensile strength of 980 MPa or more, excellent workability, high yield ratio and high strength. The hot-dip galvanized steel sheet or the alloyed hot-dip galvanized steel sheet is characterized by containing 0.12-0.3% by mass of C, 0.1% by mass or less (excluding 0% by mass) of Si, 2.0-3.5% by mass of Mn, 0.05% by mass or less (excluding 0% by mass) of P, 0.05% by mass or less (excluding 0% by mass) of S, 0.005-0.1% by mass of Al and 0.015% by mass or less (excluding 0% by mass) of N, with the balance made up of iron and unavoidable impurities. The hot-dip galvanized steel sheet or the alloyed hot-dip galvanized steel sheet is also characterized in that the metallic structure thereof contains bainite as a matrix structure, and the area ratio of ferrite is 3-20% and the area ratio of martensite is 10-35% relative to the entire structure.

## Claims

### Claim 1

A galvanized steel sheet, comprising, in mass percent:
C: 0.12-0.3%;
Si: greater than 0 and 0.1% or less;
Mn: 2.0-3.5%;
P: greater than 0 and 0.05% or less;
S: greater than 0 and 0.05% or less;
Al: 0.005-0.1%;
N: greater than 0 and 0.015% or less; with the balance being iron and unavoidable impurities, and
a hot-dip zinc plating layer or an alloyed hot-dip zinc plating layer on the surface of the galvanized steel sheet, wherein
the galvanized steel sheet has a tensile strength of 980 MPa or more, excellent workability and high yield ratio,
metallic structure thereof contains bainite as a matrix structure,
an area ratio of ferrite: 3-18%; and
an area ratio of martensite: 10-35% in terms of ratio to the entire structure.

### Claim 2 (depends on 1)

The galvanized steel sheet according to claim 1, further comprising at least one of:
Cr: greater than 0 and 1.0% or less;
Mo: greater than 0 and 1.0% or less; and
B: greater than 0 and 0.01% or less.

### Claim 3 (depends on 1)

The galvanized steel sheet according to claim 1, further comprising at least one of:
Ti: greater than 0 and 0.3% or less, and
V: greater than 0 and 0.3% or less.

### Claim 4 (depends on 1)

The galvanized steel sheet according to claim 1, comprising an area fraction of martensite: 10-30% in terms of ratio to the entire structure.

### Claim 5 (depends on 1)

The galvanized steel sheet according to claim 1, comprising C: 0.12-0.26%.

### Claim 6 (depends on 1)

The galvanized steel sheet according to claim 1, comprising C: 0.12-0.23%.

### Claim 7 (depends on 1)

The galvanized steel sheet according to claim 1, comprising Si: greater than 0 and 0.07% or less.

### Claim 8 (depends on 1)

The galvanized steel sheet according to claim 1, comprising Si: greater than 0 and 0.05% or less.

### Claim 9 (depends on 1)

The galvanized steel sheet according to claim 1, comprising Si: greater than 0 and 0.03% or less.

### Claim 10 (depends on 1)

The galvanized steel sheet according to claim 1, comprising Mn: 2.3-3.2%.

### Claim 11 (depends on 1)

The galvanized steel sheet according to claim 1, comprising P: greater than 0 and 0.03% or less.

### Claim 12 (depends on 1)

The galvanized steel sheet according to claim 1, comprising S: greater than 0 and 0.02% or less.

### Claim 13 (depends on 1)

The galvanized steel sheet according to claim 1, comprising S: greater than 0 and 0.01% or less.

### Claim 14 (depends on 1)

The galvanized steel sheet according to claim 1, comprising Al: 0.005-0.08%.

### Claim 15 (depends on 1)

The galvanized steel sheet according to claim 1, comprising Al: 0.005-0.06%.

### Claim 16 (depends on 1)

The galvanized steel sheet according to claim 1, comprising N: greater than 0 and 0.01% or less.

### Claim 17 (depends on 1)

The galvanized steel sheet according to claim 1, comprising N: greater than 0 and 0.005% or less.