# US 2014/0154128 A1 · Heat-resistant austenitic stainless steel having excellent cyclic oxidation resistance

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- Number: US 2014/0154128 A1
- Document ID: US20140154128A1
- Status: Published application
- Kind: A1
- Application number: 14/115,570
- Filed: 2012-05-10
- Published: 2014-06-05
- Earliest claimed: 2011-05-11
- Assignees: Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
- Inventors: Takeo Miyamura; Shigenobu Namba; Kazuki Furuya
- Web page: https://patentgrep.com/patent/US20140154128A1

## CPC

- C22C 38/58: with more than 1.5% by weight of manganese
- C21D 6/004: {containing Cr and Ni}
- 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 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/42: with copper
- 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: 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)

## Abstract

A heat-resistant austenitic stainless steel comprising C: 0.05 to 0.2%, Si: 0.1 to 1%, Mn: 0.1 to 2.5%, Cu: 1 to 4%, Ni: 7 to 12%, Cr: 16 to 20%, Nb: 0.1 to 0.6%, Zr: 0.05 to 0.4%, Ce: 0.005 to 0.1%, Ti: 0.1 to 0.6%, B: 0.0005 to 0.005%, N: 0.001 to 0.15%, S: 0.005% or less (not including 0%), and P: 0.05% or less (not including 0%), with the balance of iron and unavoidable impurities.

## Claims

### Claim 1

A heat-resistant austenitic stainless steel, comprising:
C in a content by mass of from 0.05 to 0.2%,
Si in a content by mass of from 0.1 to 1%,
Mn in a content by mass of from 0.1 to 2.5%,
Cu in a content by mass of from 1 to 4%,
Ni in a content by mass of from 7 to 12%,
Cr in a content by mass of from 16 to 20%,
Nb in a content by mass of from 0.1 to 0.6%,
Zr in a content by mass of from 0.05 to 0.4%,
Ce in a content by mass of from 0.005 to 0.1%,
Ti in a content by mass of from 0.1 to 0.6%,
B in a content by mass of from 0.0005 to 0.005%,
N in a content by mass of from 0.001 to 0.15%,
S in a content by mass of greater than 0% and no more than 0.005%,
P in a content by mass of greater than 0% and no more than 0.05%, and
iron.

### Claim 2 (depends on 1)

The heat-resistant austenitic stainless steel according to claim 1, further comprising:
at least one element selected from the group consisting of;
Mo in a content by mass of greater than 0% and no more than 3%,
W in a content by mass of greater than 0% and no more than 5%,
Ca in a content by mass of greater than 0% and no more than 0.005%, and
Mg in a content by mass of greater than 0% and no more than 0.005%.

### Claim 3 (depends on 1)

The heat-resistant austenitic stainless steel according to claim 1,
wherein a crystal grain size number of a microstructure is 6 or more and less than 12 in terms of ASTM grain size number.

### Claim 4 (depends on 2)

The heat-resistant austenitic stainless steel according to claim 2,
wherein a crystal grain size number of a microstructure is 6 or more and less than 12 in terms of ASTM grain size number.