# US 8,784,581 B2 · Fe-Ni alloy pipe stock and method for manufacturing the same

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- Number: US 8,784,581 B2
- Document ID: US8784581B2
- Status: Granted
- Kind: B2
- Application number: 11/643,823
- Filed: 2006-12-22
- Published: 2007-08-02
- Granted: 2014-07-22
- Earliest claimed: 2004-06-30
- Assignees: Nippon Steel & Sumitomo Metal Corporation
- Applicants: Masaaki Igarashi; Kazuhiro Shimoda; Tomio Yamakawa; Hisashi Amaya
- Inventors: Masaaki Igarashi; Kazuhiro Shimoda; Tomio Yamakawa; Hisashi Amaya
- Web page: https://patentgrep.com/patent/US8784581B2

## CPC

- C22F 1/10: of nickel or cobalt or alloys based thereon
- C21D 8/10: during manufacturing of tubular bodies
- C22C 19/055: {with the maximum Cr content being at least 20% but less than 30%}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/42: with copper
- C22C 38/44: with molybdenum or tungsten
- B21B 23/00: Tube-rolling not restricted to methods provided for in only one of groups B21B17/00, B21B19/00, B21B21/00, e.g. combined processes {planetary tube rolling, auxiliary arrangements, e.g. lubricating, special tube blanks, continuous casting combined with tube rolling}(B21B25/00 takes precedence)
- C22F: CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS (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)
- 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)
- B21B: ROLLING OF METAL (auxiliary operations used in connection with metal-working operations covered in B21, see B21C; bending by rolling B21D; manufacture of particular objects, e.g. screws, wheels, rings, barrels, balls, by rolling B21H; pressure welding by means of a rolling mill B23K20/04)

## Abstract

An Fe—Ni alloy pipe stock containing, by mass %, C≦0.04%, Si≦0.50%, Mn: 0.01 to 6.0%, P≦0.03%, S≦0.01%, Cr: 20 to 30%, Ni: 30 to 45%, Mo: 0 to 10%, W: 0 to 20%, with Mo(%)+0.5W(%): more than 1.5% to not more than 10%, Cu: 0.01 to 1.5%, Al≦0.01% and N: 0.0005 to 0.20%, and the balance being Fe, with 1440−6000P−100S−2000C≧1300, Ni+10(Mo+0.5W)+100N≦120, (Ni−35)+10(N−0.1)−2(Cr−25)−5(Mo+0.5W−3)+8≧0, can be manufactured into a seamless pipe by use of a Mannesmann piercing and rolling mill because of its excellent inner surface properties. The resulting seamless pipe has excellent mechanical properties and moreover has excellent corrosion resistance in a sour gas environment.

## Claims

### Claim 1

A method for manufacturing an Fe—Ni alloy pipe stock, comprising piercing and rolling a billet by use of a Mannesmann piercing and rolling mill, wherein the billet comprises, by mass %, C: not more than 0.04%, Si: not more than 0.50%, Mn: 0.01 to 6.0%, P: not more than 0.03%, S: not more than 0.01%, Cr: 20 to 30%, Ni: 30 to 45%, Mo: 0 to 10%, W: 0 to 20%, with Mo(%)+0.5W(%): more than 1.5% to not more than 10%, Cu: 0.01 to 1.5%, Al: not more than 0.10% and N: 0.0005 to 0.20%, and the balance being substantially Fe, with values of TGBm, Psr and Pσ represented by the following equations (1) to (3) being not less than 1300, not more than 120 and not less than 0, respectively, wherein:
TGBm=1440−6000P−100S−2000C (1),
Psr=Ni+10(Mo+0.5W)+100N (2),
Pσ=(Ni−35)+10(N−0.1)−2(Cr−25)−5(Mo+0.5W−3)+8 (3),
and further wherein each element symbol in the equations (1) to (3) represents the content by mass % of the element concerned,
wherein the piercing and rolling by the Mannesmann piercing and rolling mill is performed in a condition where the value of fn represented by the following equation (4) is not more than 1:
fn={P/(0.025H−0.01)}2+{S/(0.015H−0.01)}2 (4),
wherein P and S represent contents, by mass %, of P and S in the pipe stock, respectively, and H represents the pipe expansion ratio represented by the ratio of the outer diameter of the pipe stock to the diameter of the steel stock billet.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the content of Mn is 0.01 to 1.0% by mass %.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the billet further contains an element or elements of one or more groups selected from the groups (a) to (d) listed below in lieu of part of Fe:
(a): one or more selected from among V: 0.001 to 0.3%, Nb: 0.001 to 0.3%, Ta: 0.001 to 1.0%, Ti: 0.001 to 1.0%, Zr: 0.001 to 1.0% and Hf: 0.001 to 1.0% by mass %;
(b): B: 0.0001 to 0.015% by mass %;
(c): Co: 0.3 to 5.0% by mass %;
(d): one or more selected from among Mg: 0.0001 to 0.010%, Ca: 0.0001 to 0.010%, La: 0.0001 to 0.20%, Ce: 0.0001 to 0.20%, Y: 0.0001 to 0.40%, Sm: 0.0001 to 0.40%, Pr: 0.0001 to 0.40% and Nd: 0.0001 to 0.50% by mass %.

### Claim 4 (depends on 3)

The method according to claim 3, wherein the content of Mn is 0.01 to 1.0% by mass %.