# US 12,000,023 B2 · Methods of making corrosion resistant nickel-based alloys

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- Number: US 12,000,023 B2
- Document ID: US12000023B2
- Status: Granted
- Kind: B2
- Application number: 17/531,425
- Filed: 2021-11-19
- Published: 2022-03-10
- Granted: 2024-06-04
- Earliest claimed: 2020-03-09
- Assignees: ATI Properties, Inc.
- Applicants: ATI Properties LLC
- Inventors: Nacéra Sabrina Meck; David S. Bergstrom; John J. Dunn; David C. Berry
- Web page: https://patentgrep.com/patent/US12000023B2

## CPC

- C22C 19/055: {with the maximum Cr content being at least 20% but less than 30%}
- C21D 1/26: Methods of annealing
- C21D 6/004: {containing Cr and Ni}
- C21D 8/0226: {Hot rolling}
- C21D 8/0263: {following hot rolling}
- C21D 9/46: for sheet metals
- C22C 30/00: Alloys containing less than 50% by weight of each constituent
- C22F 1/10: of nickel or cobalt or alloys based thereon
- 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)
- 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)

## Abstract

Nickel-based alloys having improved localized corrosion resistance, improved stress-corrosion cracking (SCC) resistance and impact strength are disclosed. The improvements come from the provision of compositions that are resistant to deleterious phase formation and from the addition of alloying elements that improve corrosion resistance, impact strength, and SCC resistance. The nickel-based alloys of the present invention have controlled amounts of Ni, Cr, Fe, Mo, Co, Cu, Mn, C, N, Si, Ti, Nb, Al, and B. When subjected to post-cladding heat treatments or welding, the nickel-based alloys retain their corrosion resistance and possess desirable impact strengths.

## Claims

### Claim 1

A method of making a nickel-based alloy comprising from 38 to less than 48.0 weight percent Ni, from 19 to 25 weight percent Cr, from 15 to 35 weight percent Fe, from 0.1 to 10 weight percent Co, and from 3 to 7 weight percent Mo, the method comprising:
homogenizing an ingot of the nickel-based alloy;
working the homogenized ingot to form a slab or billet;
further hot rolling to form a plate or bar or tubular product;
annealing the product; and
cooling the annealed product, wherein the nickel-based alloy possesses at least one of the following properties:
a Charpy impact energy of at least 100 ft-lbs, measured using 5-millimeter specimens at −50° C. per ASTM E23-18;
a critical pitting temperature of greater than 95° F., measured per ASTM G48 Method C;
an intergranular corrosion rate of less than 0.25 mm/yr, measured per ASTM G28 Method A; and
a resistance to stress corrosion cracking of greater than 1,000 hrs, measured per ASTM G36.

### Claim 2 (depends on 1)

The method of claim 1, wherein the Ni comprises from 39 to 47.5 weight percent, the Cr comprises from 20 to 25 weight percent, the Fe comprises from 15 to 30 weight percent, the Mo comprises from 3.5 to 6.5 weight percent, and the Co comprises from 0.2 to 4 weight percent.

### Claim 3 (depends on 1)

The method of claim 1, wherein the Ni comprises from 40 to 47.0 weight percent, the Cr comprises from 21 to 25 weight percent, the Fe comprises from 16 to 29 weight percent, the Mo comprises from 4 to 6.5 weight percent, and the Co comprises from 0.25 to 2.6 weight percent.

### Claim 4 (depends on 1)

The method of claim 1, wherein the nickel-based alloy further comprises from 0.1 to 4 weight percent Cu, and from 0.1 to 3 weight percent Mn.

### Claim 5 (depends on 4)

The method of claim 4, wherein the nickel-based alloy further comprises less than 0.15 weight percent N, less than 1.0 weight percent Si, from 0.01 to 0.1 weight percent Ti, from 0.01 to 0.2 weight percent Nb, from 0.02 to 0.3 weight percent Al, and from 0.0002 to 0.005 weight percent B.

### Claim 6 (depends on 1)

The method of claim 1, wherein the nickel-based alloy comprises less than 0.01 weight percent Mg.

### Claim 7 (depends on 6)

The method of claim 6, wherein the nickel-based alloy further comprises from 0.01 to 0.1 weight percent Ti.

### Claim 8 (depends on 1)

The method of claim 1, wherein the nickel-based alloy comprises less than 0.3 weight percent V.

### Claim 9 (depends on 1)

The method of claim 1, wherein the nickel-based alloy comprises less than 0.3 weight percent W.

### Claim 10 (depends on 1)

The method of claim 1, wherein the nickel-based alloy contains less than or equal to 0.010 weight percent C.

### Claim 11 (depends on 1)

The method of claim 1, wherein the nickel-based alloy has a PREN of at least 40.

### Claim 12 (depends on 1)

The method of claim 1, wherein the nickel-based alloy has a Charpy impact energy of at least 100 ft-lbs, measured using 5-millimeter specimens at −50° C. per ASTM E23-18.

### Claim 13 (depends on 1)

The method of claim 1, wherein the nickel-based alloy has a critical pitting temperature of greater than 95° F., measured per ASTM G48 Method C.

### Claim 14 (depends on 1)

The method of claim 1, wherein the nickel-based alloy has an intergranular corrosion rate of less than 0.25 mm/yr, measured per ASTM G28 Method A.

### Claim 15 (depends on 1)

The method of claim 1, wherein the nickel-based alloy has a resistance to stress corrosion cracking of greater than 1,000 hrs, measured per ASTM G36.

### Claim 16 (depends on 1)

The method of claim 1, further comprising subjecting the product to a post-cladding heat treatment or a welded heat affected zone.

### Claim 17 (depends on 1)

The method of claim 1, further comprising subjecting the product to a post-cladding heat treatment.

### Claim 18

A method of making a nickel-based alloy comprising from 38 to 60 weight percent Ni, from 19 to 25 weight percent Cr, from 15 to 35 weight percent Fe, from 0.1 to 10 weight percent Co, and from 3 to 7 weight percent Mo, the method comprising:
homogenizing an ingot of the nickel-based alloy;
working the homogenized ingot to form a slab or billet;
further hot rolling to form a plate or bar or tubular product;
annealing the product; and
cooling the annealed product, wherein the nickel-based alloy possesses at least one of the following properties:
a Charpy impact energy of at least 100 ft-lbs, measured using 5-millimeter specimens at −50° C. per ASTM E23-18;
a critical pitting temperature of greater than 95° F., measured per ASTM G48 Method C;
an intergranular corrosion rate of less than 0.25 mm/yr, measured per ASTM G28 Method A;
a resistance to stress corrosion cracking of greater than 1,000 hrs, measured per ASTM G36; and
further comprising subjecting the product to a post-cladding heat treatment or a welded heat affected zone.

### Claim 19 (depends on 18)

The method of claim 18, comprising subjecting the product to the post-cladding heat treatment.

### Claim 20 (depends on 19)

The method of claim 19, wherein the post-cladding heat treated product has:
a Charpy impact energy of at least 100 ft-lbs, measured using 5-millimeter specimens at −50° C. per ASTM E23-18;
a critical pitting temperature of greater than 95° F., measured per ASTM G48 Method C;
an intergranular corrosion rate of less than 0.25 mm/yr, measured per ASTM G28 Method A; and
a resistance to stress corrosion cracking of greater than 1,000 hrs, measured per ASTM G36.

### Claim 21 (depends on 19)

The method of claim 19, wherein the post-cladding heat treated nickel-based alloy has a sigma solvus of less than 2,000° F.

### Claim 22 (depends on 21)

The method of claim 21, wherein the post-cladding heat treated nickel-based alloy has a Nv of less than 2.4.

### Claim 23 (depends on 22)

The method of claim 22, wherein the post-cladding heat treated nickel-based alloy has a Metal d of less than 0.87.

### Claim 24 (depends on 19)

The method of claim 19, wherein the post-cladding heat treated nickel-based alloy has a Charpy impact energy of at least 100 ft-lbs, measured using 5-millimeter specimens at −50° C. per ASTM E23-18.

### Claim 25 (depends on 24)

The method of claim 24, wherein the Charpy impact energy is at least 110 ft-lbs.

### Claim 26 (depends on 19)

The method of claim 19, wherein the nickel-based alloy has a Charpy impact energy, in the post-cladding heat-treated condition, that is at least 85% of a Charpy impact energy of the alloy in a solution-annealed condition, measured using 5-millimeter specimens at −50° C. per ASTM E23-18.

### Claim 27 (depends on 19)

The method of claim 19, wherein the nickel-based alloy has a Charpy impact energy, in the post-cladding heat-treated condition, that is at least 90% of a Charpy impact energy of the alloy in a solution-annealed condition, measured using 5-millimeter specimens at −50° C. per ASTM E23-18.

### Claim 28 (depends on 19)

The method of claim 19, wherein the nickel-based alloy has a Charpy impact energy in the post-cladding heat-treated condition, that is greater than or equal to a Charpy impact energy of the alloy in a solution-annealed condition, measured using 5-millimeter specimens at −50° C. per ASTM E23-18.

### Claim 29 (depends on 19)

The method of claim 19, wherein the nickel-based alloy in the post-cladding heat-treated condition has a critical pitting temperature of greater than 95° F., measured per ASTM G48 Method C.

### Claim 30 (depends on 19)

The method of claim 19, wherein the nickel-based alloy in the post-cladding heat-treated condition has an intergranular corrosion rate of less than 0.25 mm/yr, measured per ASTM G28 Method A.

### Claim 31 (depends on 19)

The method of claim 19, wherein the nickel-based alloy in the post-cladding heat-treated condition has a resistance to stress corrosion cracking of greater than 1,000 hrs, measured per ASTM G36.

### Claim 32 (depends on 19)

The method of claim 19, wherein the post-cladding heat treatment is performed at a temperature of from 1,100 to 1,800° F.

### Claim 33 (depends on 19)

The method of claim 19, wherein the post-cladding heat treatment is performed in a single stage.

### Claim 34 (depends on 19)

The method of claim 19, wherein the post-cladding heat treatment is performed in at least two stages.

### Claim 35 (depends on 34)

The method of claim 34, wherein a first stage of the post-cladding heat treatment is performed at a first temperature, a second stage of the post-cladding heat treatment is performed at a second stage of the post-cladding heat treatment, and the first temperature is higher than the second temperature.

### Claim 36 (depends on 35)

The method of claim 35, wherein the first temperature is about 1,750° F.

### Claim 37 (depends on 36)

The method of claim 36, wherein the second temperature is about 1,100° F.