Low temperature resistant oil casing having high strength and high toughness, and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-11519049-B2
Application number	US-201916982181-A
Country	US
Kind code	B2
Filing date	Mar 14, 2019
Priority date	Mar 21, 2018
Publication date	Dec 6, 2022
Grant date	Dec 6, 2022

Abstract

The present disclosure provides a low temperature resistant oil casing having high strength and high toughness, and the manufacturing method thereof, the chemical composition of the oil casing by mass of: C: 0.08-0.14%, Si: 0.1-0.4%, Mn: 0.6-1.3%, Cr: 0.5-1.5%, Mo: 0.2-0.5%, Ni: 0.2-0.5%, Nb: 0.02-0.05%, V: 0-0.1%, Al: 0.01-0.05%, Ca: 0.0005-0.005%, and the balance being Fe and unavoidable impurities. The method of manufacturing the oil casing includes: (1) smelting and continuous casting; (2) perforating and continuous rolling; (3) heat treatment, wherein an austenitizing temperature is controlled in the range of 900-930° C., and held for 30-60 min, followed by quenching, subsequently, tempering at temperature of 480-600° C., holding the temperature for 50-80 min; (4) hot sizing.

First claim

The invention claimed is:

1. An oil casing having a chemical composition by mass of:
C: 0.08-0.14%;
Si: 0.1-0.4%;
Mn: 0.6-1.3%;
Cr: 1-1.4%;
Mo: 0.2-0.5%;
Ni: 0.2-0.5%;
Nb: 0.02-0.05%;
V: 0-0.1%;
Al: 0.01-0.05%; and
Ca: 0.0005-0.005%,
balance being Fe and unavoidable impurities,
wherein the oil casing has a tensile strength of at least 1,034 MPa.

2. The oil casing according to claim 1 , which further satisfies formula:
0.3<Mn/(Cr+Mn)≤0.5,
wherein Mn and Cr respectively represent a mass percent of a corresponding element.

3. The oil casing according to claim 1 , wherein the oil casing has a microstructure of fine and uniform tempered sorbite and residual austenite.

4. The oil casing according to claim 3 , wherein a ratio of the residual austenite is 3% to 6%.

5. The oil casing according to claim 3 , wherein the oil casing has a grain size of 10 or more.

6. The oil casing according to claim 3 , wherein the oil casing has carbide particles that are finely dispersed and distributed at a grain boundary and within grains.

7. The oil casing according to claim 1 , wherein the oil casing has a yield strength ≥965 MPa, a ductile-brittle transition temperature in a range of −60° C to −100° C., a transverse impact energy under −60° C. ≥100J, a longitudinal impact energy ≥120 J, and a fracture shear ratio ≥75%.

8. An oil casing having a chemical composition by mass of:
C: 0.08-0.14%;
Si: 0.1-0.4%;
Mn: 0.6-1.3%;
Cr: 1-1.4%;
Mo: 0.2-0.5%;
Ni: 0.2-0.5%;
Nb: 0.02-0.05%;
V: 0-0.1%;
Al: 0.01-0.05%; and
Ca: 0.0005-0.005%,
balance being Fe and unavoidable impurities,
wherein the oil casing has a microstructure of fine and uniform tempered sorbite and residual austenite.

9. The oil casing having according to claim 1 , wherein the oil casing has a yield strength ≥965 MPa.

10. The oil casing having according to claim 9 , wherein the oil casing has a ductile-brittle transition temperature in a range of −60° C. to −100° C.

11. The oil casing having according to claim 10 , wherein the oil casing has a transverse impact energy under −60° C. ≥100 J.

12. The oil casing having according to claim 11 , wherein the oil casing has a longitudinal impact energy ≥120 J.

Assignees

• Baoshan Iron & Steel

Inventors

• Sun Wen
• Zhang Zhonghua
• Dong Xiaoming

Classifications

• C21D8/10 Primary

  during manufacturing of tubular bodies · CPC title

• C21D6/004

  containing Cr and Ni · CPC title

• C21D9/08 Primary

  for tubular bodies or pipes · CPC title

• C22C38/002 Primary

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title

• C22C38/02

  containing silicon · CPC title