# US 8,465,604 B2 · Ferritic stainless steel sheet having excellent corrosion resistance and method of manufacturing the same

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- Number: US 8,465,604 B2
- Document ID: US8465604B2
- Status: Granted
- Kind: B2
- Application number: 11/918,375
- Filed: 2006-07-31
- Published: 2009-03-05
- Granted: 2013-06-18
- Earliest claimed: 2005-08-17
- Assignees: Jfe Steel Corporation
- Applicants: Kazuhide Ishii; Tomohiro Ishii; Osamu Furukimi
- Inventors: Kazuhide Ishii; Tomohiro Ishii; Osamu Furukimi
- Web page: https://patentgrep.com/patent/US8465604B2

## CPC

- C21D 9/46: for sheet metals
- C21D 6/002: {containing Cr (C21D6/004 takes precedence)}
- C21D 8/02: during manufacturing of plates or strips (C21D8/12 takes precedence)
- C21D 9/48: deep-drawing sheets
- C22C 38/20: with copper
- C22C 38/28: with titanium or zirconium
- C21D 2211/005: Ferrite
- 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 ferritic stainless steel sheet having excellent corrosion resistance and a method of manufacturing the steel sheet are provided. Specifically, the ferritic stainless steel sheet of the invention contains C of 0.03% or less, Si of 1.0% or less, Mn of 0.5% or less, P of 0.04% or less, S of 0.02% or less, Al of 0.1% or less, Cr of 20.5% to 22.5%, Cu of 0.3% to 0.8%, Ni of 1.0% or less, Ti of 4×(C %+N %) to 0.35%, Nb of less than 0.01%, N of 0.03% or less, and C+N of 0.05% or less, and has the remainder including Fe and inevitable impurities, wherein 240+35×(Cr %−20.5)+280×{Ti %−4×(C %+N %)}≧280 is satisfied.

## Claims

### Claim 1

A ferritic stainless steel sheet having excellent corrosion resistance consisting of:
C of 0.03% or less,
Si of 1.0% or less,
Mn of 0.5% or less,
P of 0.04% or less,
S of 0.02% or less,
Al of 0.1% or less,
Cr of 20.5% to 22.5%,
Cu of 0.3% to 0.8%,
Ni of 1.0% or less,
Ti of 4×(C %+N %) to 0.35%,
Nb of less than 0.01%,
N of 0.03% or less,
optionally at least one of 0.0002 to 0.002% of B, 0.01 to 0.5% of V or 0.01 to 0.5% of Zr, and
C+N of 0.05% or less, and
the remainder of the steel sheet being Fe and inevitable impurities; wherein the following equation (1) is satisfied,
240+35×(Cr %−20.5)+280×{Ti %−4×(C %+N %)}≧280 (1),
wherein C %, N %, Cr % and Ti % indicate the content (mass percent) of C, N, Cr and Ti, respectively, and the steel sheet has a pitting potential equivalent of 280 or more.

### Claim 2

A method of manufacturing a ferritic stainless steel sheet having excellent corrosion resistance:
hot rolling a material consisting of:
C of 0.03% or less,
Si of 1.0% or less,
Mn of 0.5% or less,
P of 0.04% or less,
S of 0.02% or less,
Al of 0.1% or less,
Cr of 20.5% to 22.5%,
Cu of 0.3% to 0.8%,
Ni of 1.0% or less,
Ti of 4×(C %+N %) to 0.35%,
Nb of less than 0.01%,
N of 0.03% or less,
optionally at least one of 0.0002 to 0.002% of B, 0.01 to 0.5% of V or 0.01 to 0.5% of Zr, and
C+N of 0.05% or less, and
the remainder of the steel sheet being Fe and inevitable impurities, in which the following equation (1) is satisfied,
240+35×(Cr %−20.5)+280×{Ti %−4×(C %+N %)}≧280 (1),
wherein C %, N %, Cr % and Ti % indicate the content of C, N, Cr and Ti (mass percent), respectively,
into a hot-rolled sheet;
continuously annealing the hot-rolled sheet into an annealed sheet at a temperature of 800 to 1000° C.;
pickling the annealed sheet;
cold-rolling the annealed sheet to form a cold-rolled sheet; and
annealing and pickling the cold-rolled sheet in a high speed continuous annealing line for combined use with carbon steel such that the steel sheet has a pitting potential equivalent of 280 or more.

### Claim 3

A ferritic stainless steel sheet having excellent corrosion resistance comprising:
C of 0.03% or less,
Si of 1.0% or less,
Mn of 0.5% or less,
P of 0.04% or less,
S of 0.02% or less,
Al of 0.1% or less,
Cr of 20.5% to 22.5%,
Cu of 0.3% to 0.8%,
Ni of 1.0% or less,
Ti of 4×(C %+N %) to 0.35%,
Nb of less than 0.01%,
N of 0.03% or less,
optionally at least one of 0.0002 to 0.002% of B, 0.01 to 0.5% of V or 0.01 to 0.5% of Zr, and
C+N of 0.05% or less, and
the steel sheet having
the remainder including Fe and inevitable impurities;
wherein the following equation (1) is satisfied,
240+35×(Cr %−20.5)+280×{Ti %−4×(C %+N %)}≧280 (1),
wherein C %, N %, Cr % and Ti % indicate the content (mass percent) of C, N, Cr and Ti, respectively, and the steel sheet has a pitting potential equivalent of 280 or more.

### Claim 4

A method of manufacturing a ferritic stainless steel sheet having excellent corrosion resistance:
hot rolling a material comprising:
C of 0.03% or less,
Si of 1.0% or less,
Mn of 0.5% or less,
P of 0.04% or less,
S of 0.02% or less,
Al of 0.1% or less,
Cr of 20.5% to 22.5%,
Cu of 0.3% to 0.8%,
Ni of 1.0% or less,
Ti of 4×(C %+N %) to 0.35%,
Nb of less than 0.01%,
N of 0.03% or less,
optionally at least one of 0.0002 to 0.002% of B, 0.01 to 0.5% of V or 0.01 to 0.5% of Zr, and
C+N of 0.05% or less, and
the steel sheet having
the remainder including Fe and inevitable impurities,
in which the following equation (1) is satisfied,
240+35×(Cr %−20.5)+280×{Ti %−4×(C %+N %)}≧280 (1),
wherein C %, N %, Cr % and Ti % indicate the content of C, N, Cr and Ti (mass percent), respectively,
into a hot-rolled sheet;
continuously annealing the hot-rolled sheet into an annealed sheet at a temperature of 800 to 1000° C.;
pickling the annealed sheet;
cold-rolling the annealed sheet to form a cold-rolled sheet; and
annealing and pickling the cold-rolled sheet in a high speed continuous annealing line for combined use with carbon steel such that the steel sheet has a pitting potential equivalent of 280 or more.