High performance material for coiled tubing applications and the method of producing the same

• US 10,378,075 B2
• Filed: 04/02/2018
• Issued: 08/13/2019
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Tenaris Coiled Tubes, LLC (Tenaris SA)
• Original Assignee: Tenaris Coiled Tubes, LLC (Tenaris SA)
• Inventors: Valdez, Martin, Mitre, Jorge, Reichert, Bruce A.
• Primary Examiner(s): Schleis, Daniel J.
• Application Number:
  US15/943,528
• Publication Number:
  US 20180223384A1
• Time in Patent Office: 498 Days
• Field of Search: None
• CPC Class Codes: B21C 37/08 Making tubes with welded or soldered seams with helically arranged seams B21C37/122
• CPC Class Codes: C21D 1/22 Martempering
• CPC Class Codes: C21D 2211/008 Martensite
• CPC Class Codes: C21D 8/10 during manufacturing of tubular bodies
• CPC Class Codes: C21D 8/105 of ferrous alloys
• CPC Class Codes: C21D 9/08 for tubular bodies or pipes
• CPC Class Codes: C21D 9/085 Cooling or quenching
• CPC Class Codes: C21D 9/14 wear-resistant or pressure-resistant pipes
• CPC Class Codes: C21D 9/50 for welded joints
• CPC Class Codes: C21D 9/505 Cooling thereof
• CPC Class Codes: Y10T 428/12333 Helical or with helical component

Abstract

Embodiments of the present disclosure are directed to coiled steel tubes and methods of manufacturing coiled steel tubes. In some embodiments, the final microstructures of the coiled steel tubes across all base metal regions, weld joints, and heat affected zones can be homogeneous. Further, the final microstructure of the coiled steel tube can be a mixture of tempered martensite and bainite.

Claims

1. A coiled steel tube having improved yield strength and fatigue life at weld joints of the coiled steel tube, the coiled steel tube comprising:

a plurality of strips welded together end to end by a bias weld to form a plurality of bias welded strips and formed into the coiled steel tube, each of the plurality of bias welded strips having base metal regions, bias weld joints, and heat affected zones surrounding the bias weld joints;

wherein the coiled steel tube has a final microstructure formed from a full body heat treatment applied to the coiled steel tube;

wherein the final microstructure of the coiled steel tube comprises more than 90 volume % tempered martensite and 0 volume % to less than about 10 volume % bainite in the base metal regions, the bias weld joints, and the heat affected zones;

wherein the final microstructure across all base metal regions, bias weld joints, and heat affected zones is homogeneous;

wherein the hardness is substantially uniform along substantially all of a length of the coiled steel tube; and

wherein a yield strength of the coiled steel tube is greater than about 80 ksi.

2. The coiled steel tube of claim 1, wherein the tube has a yield strength of at least 110 ksi.

3. The coiled steel tube of claim 1, wherein the tube has a yield strength of at least 125 ksi.

4. The coiled steel tube of claim 1, wherein the final microstructure comprises at least 95 volume % tempered martensite and 0 volume % to less than about 5 volume % bainite in the base metal regions, the bias weld joints, and the heat affected zones.

5. The coiled steel tube of claim 1, wherein the tube has a final grain size of below 20 μ

m in the base metal regions, the bias weld joints, and the heat affected zones.

6. The coiled steel tube of claim 1, wherein the tube has a final grain size of below 15 μ

m in the base metal regions, the bias weld joints, and the heat affected zones.

7. The coiled steel tube of claim 1, wherein the fatigue life at the bias weld joints is at least about 80% of the base metal regions.

8. The coiled steel tube of claim 1, wherein a percent hardness of each of the bias weld joints, including its heat affected zone, is 110% or less than a hardness of the base metal region.

9. The coiled steel tube of claim 1, wherein the fatigue life is at least 100% greater than an equivalent grade steel which has not undergone the fully body heat treatment.

10. The coiled steel tube of claim 1, wherein the full body heat treatment applied to the coiled steel tube comprises quenching and tempering.

11. The coiled steel tube of claim 1, wherein a total length of the coiled steel tube is between 10,000 feet and 40,000 feet and the hardness is substantially uniform along substantially all of a length of the coiled steel tube including a plurality of bias weld joints.

12. The coiled steel tube of claim 1, wherein the full body heat treatment comprises at least one cycle of austenitization, quenching and tempering.

13. The coiled steel tube of claim 12, wherein the tempering is carried out at temperatures between 550 degrees C. and 720 degrees C.

14. The coiled steel tube of claim 12, wherein the austenitization is performed at temperatures between 900 degrees C. and 1000 degrees C.

15. The coiled steel tube of claim 12, wherein a cooling rate of quenching is equal to or lower than 30 degrees C./sec.

16. The coiled steel tube of claim 1, wherein the full body heat treatment comprises at least one cycle of austenitization and quenching, followed by tempering.

17. The coiled steel tube of claim 16, wherein the tempering is carried out at temperatures between 550 degrees C. and 720 degrees C.

18. The coiled steel tube of claim 16, wherein the austenitization is performed at temperatures between 900 degrees C. and 1000 degrees C.

19. The coiled steel tube of claim 16, wherein a cooling rate of quenching is equal to or lower than 30 degrees C./sec.

20. The coiled steel tube of claim 1, wherein the plurality of steel strips welded together include from about 0.010 wt. % to about 0.030 wt. % titanium and from about 0.0005 wt. % to about 0.0030 wt. % boron.

21. The coiled steel tube of claim 1, wherein the plurality of steel strips welded together include from about 0.30 wt. % to about 2.0 wt. % manganese.

22. The coiled steel tube of claim 1, wherein the plurality of steel strips welded together include from about 0.10 wt. % to about 0.35 wt. % silicon.

23. The coiled steel tube of claim 1, wherein the plurality of steel strips welded together include from about 0.16 wt. % to about 0.35 wt. % carbon.

24. The coiled steel tube of claim 1, wherein the final microstructure after full body heat treatment comprises a uniform distribution of fine carbides across the base metal regions, the bias weld, and the heat affected zones.

25. The coiled steel tube of claim 1, wherein after full body heat treatment, the coiled steel tube has a final grain size of below about 20 μ

m in the base metal region, the bias weld, and the heat affected zones.

26. The coiled steel tube of claim 25 wherein after full body heat treatment, the coiled steel tube has a final grain size of below about 15 μ

m in the base metal region, the bias weld, and the heat affected zones.

27. The coiled steel tube of claim 1, wherein the plurality of steel strips welded together include up to about 0.010 wt. % sulfur.

28. The coiled steel tube of claim 27, wherein the plurality of steel strips welded together include up to about 0.005 wt. % sulfur.

29. The coiled steel tube of claim 1, wherein the plurality of steel strips welded together include about 0.010 wt. % to about 0.040 wt. % aluminum.

30. The coiled steel tube of claim 1, wherein the plurality of steel strips welded together include up to 0.018 wt. % phosphorus.