High performance material for coiled tubing applications and the method of producing the same
AssigneeTenaris Coiled Tubes, LLC
InventorsMartín Valdez, Gonzalo Gomez, Jorge Mitre, Bruce A. Reichert
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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.
Claims22
A coiled steel tube formed from a plurality of welded strips, wherein the tube includes base metal regions, weld joints, and their heat affected zones, comprising:
- a yield strength greater than about 80 ksi;
- a composition comprising iron and:
- 0.17-0.35 wt. % carbon;
- 0.30-2.00 wt. % manganese;
- 0.10-0.30 wt. % silicon;
- 0.010-0.040 wt. % aluminum;
- up to 0.010 wt. % sulfur;
- and
- up to 0.015 wt. % phosphorus;
- and
- a final microstructure comprising a mixture of tempered martensite and bainite;
- wherein the final microstructure of the coiled tube comprises more than 90 volume % tempered martensite in the base metal regions, the weld joints, and the heat affected zones;
- wherein the final microstructure across all base metal regions, weld joints, and heat affected zones is homogeneous;
- and
- wherein the final microstructure comprises a uniform distribution of fine carbides across the base metal regions, the weld joints, and the heat affected zones.
A method of forming a coiled steel tube comprising:
- providing strips having a composition comprising iron and:
- 0.17-0.35 wt. % carbon;
- 0.30-2.00 wt. % manganese;
- 0.10-0.30 wt. % silicon;
- 0.010-0.040 wt. % aluminum;
- up to 0.010 wt. % sulfur;
- up to 0.015 wt. % phosphorus;
- and
- welding the strips together;
- forming a tube from the welded strips, wherein the tube comprises base metal regions, joint welds, and their heat affected zones;
- austenitizing the tube between 900-1000° C.;
- quenching the tube to form a final as quenched microstructure of martensite and bainite, wherein the as quenched microstructure comprises at least 90% martensite in the base metal regions, the weld joints, and the heat affected zones;
- and
- tempering the quenched tube between 550-720° C., wherein tempering of the quenched tube results in a yield strength greater than about 80 ksi;
- wherein the microstructure across all base metal regions, weld joints, and the heat affected zones is homogeneous;
- and
- wherein the microstructure comprises a uniform distribution of fine carbides across the base metal regions, the weld joints, and the heat affected zones.
Dependencies are inferred from the claim text.