Electric resistance welded steel pipe for oil well

Patent metadata

Field	Value
Publication number	US-10196702-B2
Application number	US-201415023564-A
Country	US
Kind code	B2
Filing date	Dec 11, 2014
Priority date	Dec 25, 2013
Publication date	Feb 5, 2019
Grant date	Feb 5, 2019

Abstract

An electric resistance welded steel pipe for an oil well includes in terms of mass %: 0.02 to 0.14% of C, 0.05 to 0.50% of Si, 1.0 to 2.1% of Mn, 0.020% or less of P, 0.010% or less of S, 0.010 to 0.100% of Nb, 0.010 to 0.050% of Ti, 0.010 to 0.100% of Al, and 0.0100% or less of N. Contents of Cu, Ni, Cr, Mo, V, and B are 0 to 0.50%, 0 to 1.00%, 0 to 0.50%, 0 to 0.30%, 0 to 0.10%, and 0 to 0.0030%, respectively. Remainder consisting of Fe and unavoidable impurities. In a case that a full thickness specimen is subjected to a pipe axis direction tensile test, a tensile strength is 780 MPa or more, 0.2% proof stress/tensile strength is 0.80 or more, and 2% flow stress/tensile strength is from 0.85 to 0.98.

First claim

The invention claimed is:

1. An electric resistance welded steel pipe for an oil well, comprising, in terms of mass %:
0.02 to 0.14% of C,
0.05 to 0.50% of Si,
1.0 to 2.1% of Mn,
0.020% or less of P,
0.010% or less of S,
0.010 to 0.100% of Nb,
0.010 to 0.050% of Ti,
0.010 to 0.100% of Al, and
0.0100% or less of N,
wherein contents of Cu, Ni, Cr, Mo, V, B, Ca and Ce are:
0 to 0.50% of Cu,
0 to 1.00% of Ni,
0 to 0.50% of Cr,
0 to 0.30% of Mo,
0 to 0.10% of V,
0 to 0.0030% of B,
0 to 0.0050% of Ca, and
0 to 0.0050% of Ce respectively,
a remainder consisting of Fe and unavoidable impurities,
and wherein, in a pipe axis direction tensile test with a full thickness specimen, a tensile strength is 780 MPa or more, a ratio of a 0.2% proof stress to the tensile strength [0.2% proof stress/tensile strength] is 0.80 or more, and a ratio of a 2% flow stress to the tensile strength [2% flow stress/tensile strength] is from 0.85 to 0.98.

2. The electric resistance welded steel pipe for an oil well according to claim 1 , comprising, in terms of mass %, one or more of:
more than 0 but equal to or less than 0.0050% of Ca,
more than 0 but equal to or less than 0.30% of Mo,
more than 0 but equal to or less than 0.10% of V,
more than 0 but equal to or less than 0.50% of Cr,
more than 0 but equal to or less than 1.00% of Ni,
more than 0 but equal to or less than 0.50% of Cu,
more than 0 but equal to or less than 0.0030% of B, and
more than 0 but equal to or less than 0.0050% of Ce.

3. The electric resistance welded steel pipe for an oil well according to claim 1 , wherein a residual stress measured by a Crampton method is 300 MPa or less.

4. The electric resistance welded steel pipe for an oil well according to claim 1 , wherein a weld crack sensitivity composition Pcm defined by the following Formula (1) is 0.1800 or more:
Pcm =C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B  Formula (1):

wherein, in Formula (1), each of C, Si, Mn, Cu, Ni, Cr, Mo, V, and B shows a content (mass %) of each element.

5. The electric resistance welded steel pipe for an oil well according to claim 1 , wherein an average positron lifetime measured by a positron annihilation method is from 120 ps to 140 ps.

6. The electric resistance welded steel pipe for an oil well according to claim 1 , wherein 50% or more of prior austenite grains observed in a cross section parallel to a pipe axis direction and a wall thickness direction are prior austenite grains having an aspect ratio of 1.5 or more.

7. The electric resistance welded steel pipe for an oil well according to claim 1 , wherein a base metal toughness in a circumferential direction of the pipe, determined by subjecting a full size specimen with a V-notch to a Charpy impact test, is 30 J or more at 0° C.

8. The electric resistance welded steel pipe for an oil well according to claim 2 , wherein a residual stress measured by a Crampton method is 300 MPa or less.

9. The electric resistance welded steel pipe for an oil well according to claim 2 , wherein a weld crack sensitivity composition Pcm defined by the following Formula (1) is 0.1800 or more:
Pcm =C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B  Formula (1):

wherein, in Formula (1), each of C, Si, Mn, Cu, Ni, Cr, Mo, V, and B shows a content (mass %) of each element.

10. The electric resistance welded steel pipe for an oil well according to claim 2 , wherein an average positron lifetime measured by a positron annihilation method is from 120 ps to 140 ps.

11. The electric resistance welded steel pipe for an oil well according to claim 2 , wherein 50% or more of prior austenite grains observed in a cross section parallel to a pipe axis direction and a wall thickness direction are prior austenite grains having an aspect ratio of 1.5 or more.

12. The electric resistance welded steel pipe for an oil well according to claim 2 , wherein a base metal toughness in a circumferential direction of the pipe, determined by subjecting a full size specimen with a V-notch to a Charpy impact test, is 30 J or more at 0° C.

13. The electric resistance welded steel pipe for an oil well according to claim 1 , wherein the tensile strength is more than 780 MPa.

14. The electric resistance welded steel pipe for an oil well according to claim 1 , wherein the tensile strength is 790 MPa or more.

15. The electric resistance welded steel pipe for an oil well according to claim 1 , having a wall thickness of from 5 to 17 mm, wherein a ratio [D/t] of an outer diameter (D) to a wall thickness (t) is from 10.0 to 25.0.

16. An electric resistance welded steel pipe for an oil well, comprising, in terms of mass %:
0.02 to 0.14% of C,
0.05 to 0.50% of Si,
1.0 to 2.1% of Mn,
0.020% or less of P,
0.010% or less of S,
0.010 to 0.100% of Nb,
0.010 to 0.050% of Ti,
0.010 to 0.100% of Al, and
0.0100% or less of N,
wherein contents of Cu, Ni, Cr, Mo, V, B, Ca, and Ce are:
0 to 0.50% of Cu,
0 to 1.00% of Ni,
0 to 0.50% of Cr,
0 to 0.30% of Mo,
0 to 0.10% of V,
0 to 0.0030% of B,
0 to 0.0050% of Ca, and
0 to 0.0050% of Ce respectively,
a remainder comprising Fe and unavoidable impurities,
and wherein, in a pipe axis direction tensile test with a full thickness specimen, a tensile strength is 780 MPa or more, a ratio of a 0.2% proof stress to the tensile strength [0.2% proof stress/tensile strength] is 0.80 or more, and a ratio of a 2% flow stress to the tensile strength [2% flow stress/tensile strength] is from 0.85 to 0.98.

17. The electric resistance welded steel pipe for an oil well according to claim 16 , wherein the tensile strength is more than 780 MPa.

18. The electric resistance welded steel pipe for an oil well according to claim 16 , wherein the tensile strength is 790 MPa or more.

19. The electric resistance welded steel pipe for an oil well according to claim 16 , having a wall thickness of from 5 to 17 mm, wherein a ratio [D/t] of an outer diameter (D) to a wall thickness (t) is from 10.0 to 25.0.

Assignees

• Nippon Steel & Sumitomo Metal Corp

Inventors

• Fukushi Takaaki
• Hamatani Hideki
• Ozaki Masakazu
• Ichinose Yuusuke

Classifications

• C21D8/10

  during manufacturing of tubular bodies · CPC title

• C21D8/105

  Chemistry & Metallurgy · mapped topic

• B23K2101/10

  Pipe-lines · CPC title

• B23K2103/04

  Steel {or steel} alloys · CPC title

• C22C38/24

  with vanadium · CPC title