# US 12,371,766 B2 · Martensitic stainless alloy

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- Number: US 12,371,766 B2
- Document ID: US12371766B2
- Status: Granted
- Kind: B2
- Application number: 17/614,709
- Filed: 2020-06-04
- Published: 2022-07-28
- Granted: 2025-07-29
- Earliest claimed: 2019-06-05
- Assignees: Alleima StripTech AB
- Applicants: Alleima Striptech AB
- Inventors: Sara Wiklund; Jonas Nilsson; Sven-Inge Mattsson; Anders Hoel; Guocai Chai
- Web page: https://patentgrep.com/patent/US12371766B2

## CPC

- C22C 38/46: with vanadium
- C21D 1/18: Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62)
- C21D 1/25: Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
- C21D 1/26: Methods of annealing
- C21D 6/002: {containing Cr (C21D6/004 takes precedence)}
- C21D 6/004: {containing Cr and Ni}
- C21D 6/005: {containing Mn}
- C21D 6/008: {containing Si}
- C21D 6/02: Hardening by precipitation
- C21D 8/02: during manufacturing of plates or strips (C21D8/12 takes precedence)
- C21D 8/021: involving particular fabrication steps or treatments of ingots or slabs
- C21D 8/0226: {Hot rolling}
- C21D 8/0236: {Cold rolling}
- C21D 8/0263: {following hot rolling}
- C21D 8/0273: {Final recrystallisation annealing}
- C21D 9/46: for sheet metals
- C21D 9/52: for wires; for strips {; for rods of unlimited length}
- 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 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/20: with copper
- C22C 38/22: with molybdenum or tungsten
- C22C 38/24: with vanadium
- C22C 38/42: with copper
- C22C 38/44: with molybdenum or tungsten
- C21D 6/04: Hardening by cooling below 0 degrees Celsius
- C21D 8/0268: {between cold rolling steps}
- C21D 2211/004: Dispersions; Precipitations
- C21D 2211/008: Martensite
- C21D 2261/00: Machining or cutting being involved
- 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 martensitic stainless alloy comprising, in percent by weight (wt. %) C >0.50 to 0.60; Si 0.10 to 0.60, Mn 0.40 to 0.80; Cr 13.50 to 14.50; Ni 0 to 1.20; Mo 0.80 to 2.50; N 0.050 to 0.12; Cu 0.10 to 1.50; V max 0.10; S max 0.03; P max 0.03; the balance being Fe an unavoidable impurities.

## Claims

### Claim 1

A martensitic stainless alloy comprising, in percent by weight (wt. %):
C
>0.50 to 0.60;
Si
0.10 to 0.60,
Mn
0.40 to 0.80;
Cr
13.50 to 14.50;
Ni
0 to 1.20;
Mo
0.80 to 2.50;
N
0.050 to 0.12;
Cu
more than 0.4 to 1.50;
V
max 0.10;
S
max 0.03;
P
max 0.03;
the balance being Fe and unavoidable impurities,
wherein a microstructure of the martensitic stainless alloy includes a plurality of particles selected from the group consisting of metal carbonitrides; M23C6 and M7C3 carbides; and carbides of other types, where M represents one or more metallic atoms, and
wherein a particle density of the plurality of particles is 56-58 per 100 μm2, a particle area fraction is 4.1 to 5.0%, a max particle diameter is 1.07 μm, and a volume fraction of particles having a diameter above 0.70 μm is 6-15%.

### Claim 2 (depends on 1)

The martensitic stainless alloy according to claim 1, wherein the content of Si is 0.20 to 0.55 wt. %.

### Claim 3 (depends on 1)

The martensitic stainless alloy according to claim 1, wherein the content of Mn is 0.50 to 0.80 wt. %.

### Claim 4 (depends on 1)

The martensitic stainless alloy according to claim 1, wherein the content of Mo is 0.90 to 1.30 wt. %.

### Claim 5 (depends on 1)

The martensitic stainless alloy according to claim 1, wherein the Ni content is <0.80 wt. %.

### Claim 6 (depends on 1)

The martensitic stainless alloy according to claim 1, wherein the N content is 0.050 to 0.10 wt. %.

### Claim 7 (depends on 1)

The martensitic stainless alloy according to claim 1, wherein the V content is 0.030-0.10 wt. %.

### Claim 8 (depends on 1)

The martensitic stainless alloy according to claim 1, wherein the C content is 0.51-0.60 wt. %.

### Claim 9 (depends on 1)

The martensitic stainless alloy according s claim 1, wherein the stainless alloy comprises 0.50-1.5 wt. % Cu.

### Claim 10 (depends on 1)

The martensitic stainless alloy according to claim 1, wherein the microstructure includes Cu precipitates.

### Claim 11 (depends on 1)

The martensitic stainless alloy according to claim 1, wherein:
Si is 0.20 to 0.55 wt. %,
Mn is 0.50 to 0.80 wt. %,
Mo is 0.80 to 2.00 wt. %,
Ni is <0.80 wt. %,
N is 0.050 to 0.10 wt. %,
V is 0.030 to 0.10 wt. %,
C is 0.51 to 0.60 wt. %, and
Cu is 0.50 to 1.5 wt. %.

### Claim 12 (depends on 11)

The martensitic stainless alloy according to claim 11, wherein the content of Mo is 0.90 to 1.30 wt. %.

### Claim 13 (depends on 12)

An object comprising the martensitic stainless alloy according to claim 12.

### Claim 14 (depends on 10)

The martensitic stainless alloy according to claim 10, wherein the Cu precipitates have an average area of 0.012 μm2 and an average diameter of 0.12 μm, and wherein a particle density of the Cu precipitates is 7 per 100 μm2.

### Claim 15 (depends on 1)

The martensitic stainless alloy according to claim 1, wherein the martensitic stainless alloy has a fatigue limit of 1505 MPa.

### Claim 16 (depends on 1)

The martensitic stainless alloy according to claim 1, wherein the metallic atoms include Cr and Mo.

### Claim 17 (depends on 1)

A stainless steel object comprising the martensitic stainless alloy according to claim 1.

### Claim 18 (depends on 17)

The stainless steel object according to claim 17, wherein the object is a strip.

### Claim 19 (depends on 18)

The stainless steel object according to claim 18, wherein said object is cold rolled, hardened and tempered.

### Claim 20 (depends on 19)

The stainless steel object according to claim 19, wherein said object is cold rolled to final thicknesses of 0.040 to 3 mm.

### Claim 21

A flapper valve for a compressor, comprising:
a flapper valve body formed of a martensitic stainless alloy, the martensitic stainless alloy having a composition including, in percent by weight (wt. %):
C >0.50 to 0.60;
Si 0.10 to 0.60;
Mn 0.40 to 0.80;
Cr 13.50 to 14.50;
Ni 0 to 1.20;
Cu more than 0.4 to 1.50;
V max 0.10;
S max 0.03;
P max 0.03;
the balance being Fe and unavoidable impurities,
wherein a microstructure of the martensitic stainless alloy includes a plurality of particles selected from the group consisting of metal carbonitrides; M23C6 and M7C3 carbides; and carbides of other types, where M represents one or more metallic atoms, and
wherein a particle density of the plurality of particles is 56-58 per 100 μm2, a particle area fraction is 4.1 to 5.0%, a max particle diameter is 1.07 μm, and a volume fraction of particles having a diameter above 0.70 μm is 6-15%.

### Claim 22 (depends on 21)

The flapper valve according to claim 21, wherein the martensitic stainless alloy has a fatigue limit of 1481 to 1527 MPa.

### Claim 23 (depends on 21)

The flapper valve according to claim 21, wherein the composition includes, in percent by weight (wt. %):
C 0.51 to 0.56;
Si 0.30 to 0.50;
Mn 0.60 to 0.80;
Cr 13.50 to 14.50;
Ni 0 to 0.80;
Mo 0.90 to 1.30;
N 0.050 to 0.090;
Cu more than 0.4 to 1.60;
V 0.030 to 0.10;
S max 0.03;
P max 0.03;
the balance being Fe and less than or equal to 0.5 wt. % unavoidable impurities.