# US 12,215,411 B2 · Coated steel member, coated steel sheet, and methods for producing same

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- Number: US 12,215,411 B2
- Document ID: US12215411B2
- Status: Granted
- Kind: B2
- Application number: 18/348,163
- Filed: 2023-07-06
- Published: 2023-11-02
- Granted: 2025-02-04
- Earliest claimed: 2019-11-22
- Assignees: Nippon Steel Corporation
- Applicants: Nippon Steel Corporation
- Inventors: Shinichiro Tabata
- Web page: https://patentgrep.com/patent/US12215411B2

## CPC

- C22C 38/54: with boron
- B32B 15/012: {one layer being formed of an iron alloy or steel, another layer being formed of aluminium or an aluminium alloy}
- C21D 1/18: Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62)
- C21D 1/26: Methods of annealing
- C21D 1/76: Adjusting the composition of the atmosphere
- C21D 8/02: during manufacturing of plates or strips (C21D8/12 takes precedence)
- C21D 8/0226: {Hot rolling}
- C21D 8/0236: {Cold rolling}
- C21D 8/0247: characterised by the heat treatment
- C21D 8/0257: {with diffusion of elements, e.g. decarburising, nitriding}
- C21D 8/0278: involving a particular surface treatment (C21D8/0294 takes precedence)
- C21D 9/46: for sheet metals
- 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 38/005: {containing rare earths, i.e. Sc, Y, Lanthanides}
- C22C 38/008: {containing tin}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/08: containing nickel {(C22C38/105 takes precedence)}
- C22C 38/12: containing tungsten, tantalum, molybdenum, vanadium, or niobium
- C22C 38/14: containing titanium or zirconium
- C22C 38/16: containing copper
- C22C 38/42: with copper
- C22C 38/44: with molybdenum or tungsten
- C22C 38/46: with vanadium
- C22C 38/48: with niobium or tantalum
- C22C 38/50: with titanium or zirconium
- C22C 38/60: containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
- C23C 2/02: Pretreatment of the material to be coated, e.g. for coating on selected surface areas (C23C2/30 takes precedence)
- 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 10/02: Pretreatment of the material to be coated (C23C10/04 takes precedence)
- C23C 10/28: using solids, e.g. powders, pastes
- 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}
- C21D 2211/008: Martensite
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- 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)
- 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

A coated steel member includes: a steel sheet substrate containing, as a chemical composition, by mass %, C: 0.25% to 0.65%, Si: 0.10% to 1.00%, Mn: 0.30% to 1.00%, P: 0.050% or less, S: 0.0100% or less, N: 0.010% or less, Ti: 0.010% to 0.100%, B: 0.0005% to 0.0100%, Nb: 0.02% to 0.10%, Mo: 0.10% to 1.00%, Cu: 0.15% to 1.00%, and Ni: 0.05% to 0.25%; and a coating formed on a surface of the steel sheet substrate and containing Al and Fe. The maximum Cu content in a range from the surface to a depth of 5.0 μm is 150% or more of the Cu content of the steel sheet substrate.

## Claims

### Claim 1

A coated steel sheet comprising:
a steel sheet containing, as a chemical composition, by mass %,
C: 0.25% to 0.65%,
Si: 0.10% to 1.00%,
Mn: 0.30% to 1.00%,
P: 0.050% or less,
S: 0.0100% or less,
N: 0.010% or less,
Ti: 0.010% to 0.100%,
B: 0.0005% to 0.0100%,
Nb: 0.02% to 0.10%,
Mo: 0.10% to 1.00%,
Cu: 0.15% to 1.00%,
Ni: 0.05% to 0.25%,
Cr: 0% to 1.00%,
V: 0% to 1.00%,
Ca: 0% to 0.010%,
Al: 0% to 1.00%,
Sn: 0% to 1.00%,
W: 0% to 1.00%,
Sb: 0% to 1.00%,
Zr: 0% to 1.00%,
REM: 0% to 0.30%, and
a remainder consisting of Fe and impurities;
a coating on a surface of the steel sheet and containing Al; and
a boundary portion formed between the steel sheet and the coating,
wherein a maximum Cu content of the boundary portion is 80% or more of an average Cu content of the steel sheet.

### Claim 2

A method for producing a coated steel sheet, the method comprising:
melting and casting a steel containing, as a chemical composition, by mass %, C: 0.25% to 0.65%, Si: 0.10% to 1.00%, Mn: 0.30% to 1.00%, P: 0.050% or less, S: 0.0100% or less, N: 0.010% or less, Ti: 0.010% to 0.100%, B: 0.0005% to 0.0100%, Nb: 0.02% to 0.10%, Mo: 0.10% to 1.00%, Cu: 0.15% to 1.00%, Ni: 0.05% to 0.25%, Cr: 0% to 1.00%, V: 0% to 1.00%, Ca: 0% to 0.010%, Al: 0% to 1.00%, Sn: 0% to 1.00%, W: 0% to 1.00%, Sb: 0% to 1.00%, Zr: 0% to 1.00%, REM: 0% to 0.30%, and a remainder consisting of Fe and impurities, to obtain a slab;
hot-rolling the slab into a hot-rolled steel sheet;
coiling the hot-rolled steel sheet;
as necessary, annealing the hot-rolled steel sheet;
as necessary, descaling the hot-rolled steel sheet and cold-rolling the hot-rolled steel sheet into a cold-rolled steel sheet;
as necessary, annealing the hot-rolled steel sheet or the cold-rolled steel sheet into an annealed steel sheet; and
forming an Al-based coating by immersing the hot-rolled steel sheet, the cold-rolled steel sheet, or the annealed steel sheet in an Al-based plating bath having a bath temperature of 600° C. or higher, and then cooling the hot-rolled steel sheet, the cold-rolled steel sheet, or the annealed steel sheet to 200° C. or lower at an average cooling rate of slower than 30° C./s.

### Claim 3 (depends on 2)

The method for producing a coated steel sheet according to claim 2, further comprising:
post-heating to anneal the coated steel sheet obtained by the forming of the Al-based coating, in a temperature range of 450° C. to 800° C.