# US 2010/0166594 A1 · Austenitic heat resistant alloy

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- Number: US 2010/0166594 A1
- Document ID: US20100166594A1
- Status: Published application
- Kind: A1
- Application number: 12/647,028
- Filed: 2009-12-24
- Published: 2010-07-01
- Earliest claimed: 2008-12-25
- Assignees: Sumitomo Metal Industries, Ltd.
- Inventors: Hiroyuki Hirata; Atsuro Iseda; Hirokazu Okada; Hiroyuki Semba; Kaori Kawano; Osamu Miyahara
- Web page: https://patentgrep.com/patent/US20100166594A1

## CPC

- C22C 38/44: with molybdenum or tungsten
- C21D 6/001: {containing Ni (C21D6/004 takes precedence)}
- C21D 6/002: {containing Cr (C21D6/004 takes precedence)}
- 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 38/008: {containing tin}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/50: with titanium or zirconium
- C22C 38/52: with cobalt
- C22C 38/54: with boron
- F22B 37/04: and characterised by material, e.g. use of special steel alloy
- 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)
- F22B: METHODS OF STEAM GENERATION; STEAM BOILERS

## Abstract

An austenitic heat resistant alloy, which comprises, by mass percent, C≦0.15%, Si≦2%, Mn≦3%, Ni: 40 to 80%, Cr: 15 to 40%, W and Mo: 1 to 15% in total content, Ti≦3%, Al≦3%, N≦0.03%, O≦0.03%, with the balance being Fe and impurities, and among the impurities P≦0.04%, S≦0.03%, Sn≦0.1%, As≦0.01%, Zn≦0.01%, Pb≦0.01% and Sb≦0.01%, and satisfies the conditions [P1=S+{(P+Sn)/2}+{(As+Zn+Pb+Sb)/5}≦0.050], [0.2≦P2=Ti+2Al≦7.5−10×P1], [P2≦9.0−100×O] and [N≦0.002×P2+0.019] can prevent both the liquation crack in the HAZ and the brittle crack in the HAZ and also can prevent defects due to welding fabricability, which occur during welding fabrication, and moreover has excellent creep strength at high temperatures. Therefore, the alloy can be used suitably as a material for constructing high temperature machines and equipment, such as power generating boilers, plants for the chemical industry and so on. The ally may contain a specific amount or amounts of one or more elements selected from Co, B, Ta, Hf, Nb, Zr, Ca, Mg, Y, La, Ce and Nd.

## Claims

### Claim 1

An austenitic heat resistant alloy, which comprises, by mass percent, C: not more than 0.15%, Si: not more than 2%, Mn: not more than 3%, Ni: 40 to 80%, Cr: 15 to 40%, W and Mo: 1 to 15% in total content, Ti: not more than 3%, Al: not more than 3%, N: not more than 0.03% and O: not more than 0.03%, with the balance being Fe and impurities, in which the contents of P, 5, Sn As, Zn, Pb and Sb among the impurities are P: not more than 0.04%, S: not more than 0.03%, Sn: not more than 0.1%, As: not more than 0.01%, Zn: not more than 0.01%, Pb: not more than 0.01% and Sb: not more than 0.01%, and the value of P1 defined by the following formula (1) and the value of P2 defined by the following formula (2) satisfy the relationships expressed by the following formulas (3) to (6);
P1=S+{(P+Sn)/2}+{(As+Zn+Pb+Sb)/5} (1),
P2=Ti+2Al (2),
P1≦0.050 (3),
0.2≦P2≦7.5−10×P1 (4),
P2≦9.0−100×O (5),
N≦0.002×P2+0.019 (6);
wherein each element symbol in the formulas represents the content by mass percent of the element concerned.

### Claim 2 (depends on 1)

The austenitic heat resistant alloy according to claim 1, which contains, by mass percent, Co: not more than 20% in lieu of a part of Fe.

### Claim 3 (depends on 1)

The austenitic heat resistant alloy according to claim 1, which contains, by mass percent, one or more elements of one or more groups selected from the first to third groups listed below in lieu of a part of Fe:
First group: B: not more than 0.01%;
Second group: Ta: not more than 0.1%, Hf: not more than 0.1%, Nb: not more than 0.1% and Zr: not more than 0.2%; and
Third group: Ca: not more than 0.02%, Mg: not more than 0.02%, Y: not more than 0.1%, La: not more than 0.1%, Ce: not more than 0.1% and Nd: not more than 0.1%.

### Claim 4 (depends on 2)

The austenitic heat resistant alloy according to claim 2, which contains, by mass percent, one or more elements of one or more groups selected from the first to third groups listed below in lieu of a part of Fe:
First group: B: not more than 0.01%;
Second group: Ta: not more than 0.1%, Hf: not more than 0.1%, Nb: not more than 0.1% and Zr: not more than 0.2%; and
Third group: Ca: not more than 0.02%, Mg: not more than 0.02%, y: not more than 0.1%, La: not more than 0.1%, Ce: not more than 0.1% and Nd: not more than 0.1%.