# US 2019/0376167 A1 · Steel Material and Method for Producing Steel Material

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- Number: US 2019/0376167 A1
- Document ID: US20190376167A1
- Status: Published application
- Kind: A1
- Application number: 16/476,704
- Filed: 2018-01-22
- Published: 2019-12-12
- Earliest claimed: 2017-01-24
- Assignees: Nippon Steel Corporation
- Applicants: Nippon Steel Corporation
- Inventors: Shinji Yoshida; Yuji Arai; Atsushi Soma; Hiroki Kamitani
- Web page: https://patentgrep.com/patent/US20190376167A1

## CPC

- C22C 38/001: {containing N}
- C22C 38/42: with copper
- C21D 6/004: {containing Cr and Ni}
- C21D 6/005: {containing Mn}
- C21D 6/008: {containing Si}
- C21D 8/00: Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02)
- C21D 8/10: during manufacturing of tubular bodies
- C21D 9/085: {Cooling or quenching}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/22: with molybdenum or tungsten
- C22C 38/24: with vanadium
- C22C 38/26: with niobium or tantalum
- C22C 38/28: with titanium or zirconium
- C22C 38/32: with boron
- C22C 38/44: with molybdenum or tungsten
- C22C 38/46: with vanadium
- C22C 38/48: with niobium or tantalum
- C22C 38/50: with titanium or zirconium
- C22C 38/52: with cobalt
- 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

The steel material according to the present disclosure contains a chemical composition consisting of, in mass %, C: more than 0.50 to 0.80%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P: 0.025% or less, S: 0.0100% or less, Al: 0.005 to 0.100%, Cr: 0.20 to 1.50%, Mo: 0.25 to 1.50%, Ti: 0.002 to 0.050%, B: 0.0001 to 0.0050%, N: 0.002 to 0.010% and O: 0.0100% or less, with the balance being Fe and impurities. The steel material contains an amount of dissolved C within a range of 0.010 to 0.060 mass %. The steel material also has a yield strength within a range of 965 to 1069 MPa, and a yield ratio of the steel material is 90% or more.

## Claims

### Claim 1

A steel material comprising:
a chemical composition consisting of, in mass %,
C: more than 0.50 to 0.80%,
Si: 0.05 to 1.00%,
Mn: 0.05 to 1.00%,
P: 0.025% or less,
S: 0.0100% or less,
Al: 0.005 to 0.100%,
Cr: 0.20 to 1.50%,
Mo: 0.25 to 1.50%,
Ti: 0.002 to 0.050%,
B: 0.0001 to 0.0050%,
N: 0.002 to 0.010%,
O: 0.0100% or less,
V: 0 to 0.30%,
Nb: 0 to 0.100%,
Ca: 0 to 0.0100%,
Mg: 0 to 0.0100%,
Zr: 0 to 0.0100%,
Co: 0 to 0.50%,
W: 0 to 0.50%,
Ni: 0 to 0.50%, and
Cu: 0 to 0.50%
with the balance being Fe and impurities,
an amount of dissolved C within a range of 0.010 to 0.060 mass %,
a yield strength within a range of 965 to 1069 MPa, and
a yield ratio of 90% or more.

### Claim 2 (depends on 1)

The steel material according to claim 1, wherein the chemical composition contains one or more types of element selected from the group consisting of:
V: 0.01 to 0.30%, and
Nb: 0.002 to 0.100%.

### Claim 3 (depends on 1)

The steel material according to claim 1, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Ca: 0.0001 to 0.0100%,
Mg: 0.0001 to 0.0100%, and
Zr: 0.0001 to 0.0100%.

### Claim at position 4

4-8. (canceled)

### Claim 9 (depends on 2)

The steel material according to claim 2, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Ca: 0.0001 to 0.0100%,
Mg: 0.0001 to 0.0100%, and
Zr: 0.0001 to 0.0100%.

### Claim 10 (depends on 1)

The steel material according to claim 1, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Co: 0.02 to 0.50%, and
W: 0.02 to 0.50%.

### Claim 11 (depends on 2)

The steel material according to claim 2, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Co: 0.02 to 0.50%, and
W: 0.02 to 0.50%.

### Claim 12 (depends on 3)

The steel material according to claim 3, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Co: 0.02 to 0.50%, and
W: 0.02 to 0.50%.

### Claim 13 (depends on 9)

The steel material according to claim 9, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Co: 0.02 to 0.50%, and
W: 0.02 to 0.50%.

### Claim 14 (depends on 1)

The steel material according to claim 1, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Ni: 0.02 to 0.50%, and
Cu: 0.01 to 0.50%.

### Claim 15 (depends on 2)

The steel material according to claim 2, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Ni: 0.02 to 0.50%, and
Cu: 0.01 to 0.50%.

### Claim 16 (depends on 3)

The steel material according to claim 3, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Ni: 0.02 to 0.50%, and
Cu: 0.01 to 0.50%.

### Claim 17 (depends on 9)

The steel material according to claim 9, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Ni: 0.02 to 0.50%, and
Cu: 0.01 to 0.50%.

### Claim 18 (depends on 10)

The steel material according to claim 10, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Ni: 0.02 to 0.50%, and
Cu: 0.01 to 0.50%.

### Claim 19 (depends on 11)

The steel material according to claim 11, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Ni: 0.02 to 0.50%, and
Cu: 0.01 to 0.50%.

### Claim 20 (depends on 12)

The steel material according to claim 12, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Ni: 0.02 to 0.50%, and
Cu: 0.01 to 0.50%.

### Claim 21 (depends on 13)

The steel material according to claim 13, wherein the chemical composition contains one or more types of element selected from the group consisting of:
Ni: 0.02 to 0.50%, and
Cu: 0.01 to 0.50%.

### Claim 22 (depends on 1)

The steel material according to claim 1, wherein the steel material is an oil-well steel pipe.

### Claim 23 (depends on 1)

A method for producing a steel material, comprising:
a preparation process of preparing an intermediate steel material containing a chemical composition according to claim 1,
a quenching process of, after the preparation process, cooling the intermediate steel material that is at a temperature in a range of 800 to 1000° C. at a cooling rate of 50° C./min; and
a tempering process of holding the intermediate steel material after quenching at a temperature in a range of 660° C. to an Ac1 point for 10 to 90 minutes, and thereafter cooling the intermediate steel material at an average cooling rate in a temperature region from 600° C. to 200° C. of 5 to 300° C./sec.

### Claim 24 (depends on 1, 23)

The method for producing a steel material according to claim 23, wherein the preparation process includes:
a starting material preparation process of preparing a starting material containing a chemical composition according to claim 1, and
a hot working process of subjecting the starting material to hot working to produce an intermediate steel material.