High-strength low-alloy steel excellent in high-pressure hydrogen environment embrittlement resistance characteristics and method for producing the same

Patent metadata

Field	Value
Publication number	US-10227682-B2
Application number	US-201514616064-A
Country	US
Kind code	B2
Filing date	Feb 6, 2015
Priority date	May 13, 2008
Publication date	Mar 12, 2019
Grant date	Mar 12, 2019

Abstract

An object of the present invention is to provide at a low cost a low-alloy steel having a high strength and excellent high-pressure hydrogen environment embrittlement resistance characteristics under a high-pressure hydrogen environment. The invention is a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics, which has a composition comprising C: 0.10 to 0.20% by mass, Si: 0.10 to 0.40% by mass, Mn: 0.50 to 1.20% by mass, Ni: 0.75 to 1.75% by mass, Cr: 0.20 to 0.80% by mass, Cu: 0.10 to 0.50% by mass, Mo: 0.10 to 1.00% by mass, V: 0.01 to 0.10% by mass, B: 0.0005 to 0.005% by mass and N: 0.01% by mass or less, and further comprising one or two of Nb: 0.01 to 0.10% by mass and Ti: 0.005 to 0.050% by mass, with the balance consisting of Fe and unavoidable impurities.

First claim

What is claimed is:

1. A method for producing a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics, the method comprising:
melting an alloy steel material having a composition comprising C: 0.10 to 0.20% by mass, Si: 0.10 to 0.40% by mass, Mn: 0.50 to 1.20% by mass, Ni: 0.75 to 1.75% by mass, Cr: 0.20 to 0.80% by mass, Cu: 0.10 to 0.50% by mass, Mo: 0.10 to 1.00% by mass, V: 0.01 to 0.10% by mass, B: 0.0005 to 0.005% by mass and N: 0.01% by mass or less, and further comprising one or two of Nb: 0.01 to 0.10% by mass and Ti: 0.005 to 0.050% by mass, with the balance consisting of Fe and unavoidable impurities to form a steel ingot;
subjecting the steel ingot to hot-working to provide a hot-worked material;
after the hot-working, performing normalizing at 1,000° C. to 1,100° C. to homogenize a structure, wherein the normalizing is performed by heating the hot-worked material at 1,000° C. to 1,100° C. and then cooling;
after the normalizing, performing quenching from the temperature range of 880° C. to 900° C. to impart an optimum crystal grain size, wherein the quenching is performed by heating to 880° C. to 900° C. and then cooling; and
after the quenching, performing tempering at 560° C. to 580° C. to impart an optimum tensile strength, wherein the tempering is performed by heating to 560° C. to 580° C.

2. A method for producing a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics according to claim 1 , wherein the composition comprises C: 0.10 to 0.20% by mass, Si: 0.10 to 0.40% by mass, Mn: 0.50 to 1.20% by mass, Ni: 0.75 to 1.75% by mass, Cr: 0.20 to 0.80% by mass, Cu: 0.10 to 0.50% by mass, Mo: 0.10 to 1.00% by mass, V: 0.01 to 0.10% by mass, B: 0.0005 to 0.005% by mass and N: 0.01% by mass or less, and further comprises Nb: 0.01 to 0.10% by mass and Ti: 0.005 to 0.050% by mass, with the balance consisting of Fe and unavoidable impurities.

3. A method for producing a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics according to claim 1 , wherein the composition comprises C: 0.10 to 0.20% by mass, Si: 0.10 to 0.40% by mass, Mn: 0. 50 to 1.20% by mass, Ni: 0.75 to 1.75% by mass, Cr: 0.20 to 0.80% by mass, Cu: 0.10 to 0.50% by mass, Mo: 0.10 to 1.00% by mass, V: 0.01 to 0.10% by mass, B: 0.0005 to 0.005% by mass and N: 0.01% by mass or less, and further comprises Ti: 0.005 to 0.050% by mass, with the balance consisting of Fe and unavoidable impurities.

4. A method for producing a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics according to claim 1 , wherein the composition further comprises Ti: 0.012 to 0.032% by mass.

5. A method for producing a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics according to claim 1 , wherein the composition further comprises Ti: 0.032 to 0.050% by mass.

6. A method for producing a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics, the method consisting of:
melting an alloy steel material having a composition comprising C: 0.10 to 0.20% by mass, Si: 0.10 to 0.40% by mass, Mn: 0.50 to 1.20% by mass, Ni: 0.75 to 1.75% by mass, Cr: 0.20 to 0.80% by mass, Cu: 0.10 to 0.50% by mass, Mo: 0.10 to 1.00% by mass, V: 0.01 to 0.10% by mass, B: 0.0005 to 0.005% by mass and N: 0.01% by mass or less, and further comprising one or two of Nb: 0.01 to 0.10% by mass and Ti: 0.005 to 0.050% by mass, with the balance consisting of Fe and unavoidable impurities to form a steel ingot;
subjecting the steel ingot to hot-working to provide a hot-worked material;
after the hot-working, performing normalizing at 1,000° C. to 1,100° C. to homogenize a structure, wherein the normalizing is performed by heating the hot-worked material at 1,000° C. to 1,100° C. and then cooling;
after the normalizing, performing quenching from the temperature range of 880° C. to 900° C. to impart an optimum crystal grain size, wherein the quenching is performed by heating to 880° C. to 900° C. and then cooling; and
after the quenching, performing tempering at 560° C. to 580° C. to impart an optimum tensile strength, wherein the tempering is performed by heating to 560° C. to 580° C.

7. A method for producing a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics according to claim 6 , wherein the composition comprises C: 0.10 to 0.20% by mass, Si: 0.10 to 0.40% by mass, Mn: 0.50 to 1.20% by mass, Ni: 0.75 to 1.75% by mass, Cr: 0.20 to 0.80% by mass, Cu: 0.10 to 0.50% by mass, Mo: 0.10 to 1.00% by mass, V: 0.01 to 0.10% by mass, B: 0.0005 to 0.005% by mass and N: 0.01% by mass or less, and further comprises Nb: 0.01 to 0.10% by mass and Ti: 0.005 to 0.050% by mass, with the balance consisting of Fe and unavoidable impurities.

8. A method for producing a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics according to claim 6 , wherein the composition comprises C: 0.10 to 0.20% by mass, Si: 0.10 to 0.40% by mass, Mn: 0. 50 to 1.20% by mass, Ni: 0.75 to 1.75% by mass, Cr: 0.20 to 0.80% by mass, Cu: 0.10 to 0.50% by mass, Mo: 0.10 to 1.00% by mass, V: 0.01 to 0.10% by mass, B: 0.0005 to 0.005% by mass and N: 0.01% by mass or less, and further comprises Ti: 0.005 to 0.050% by mass, with the balance consisting of Fe and unavoidable impurities.

9. A method for producing a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics according to claim 6 , wherein the composition further comprises Ti: 0.012 to 0.032% by mass.

10. A method for producing a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics according to claim 6 , wherein the composition further comprises Ti: 0.032 to 0.050% by mass.

11. A method for producing a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics according to claim 1 , wherein Al is not present in the composition of the alloy steel material.

12. A method for producing a high-strength low-alloy steel having high-pressure hydrogen environment embrittlement resistance characteristics according to claim 6 , wherein Al is not present in the composition of the alloy steel material.

Assignees

• Japan Steel Works Ltd

Inventors

• Takasawa Kouichi
• Wada Yoru
• Ishigaki Ryoji
• Tanaka Yasuhiko

Classifications

• C22C38/54 Primary

  with boron · CPC title

• C22C38/46

  with vanadium · CPC title

• C22C38/001

  containing N · CPC title

• C22C38/50

  with titanium or zirconium · CPC title

• C22C38/44

  with molybdenum or tungsten · CPC title