High performance material for coiled tubing applications and the method of producing the same
First Claim
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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 yield strength following manufacture of the coiled steel tube 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.
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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.
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Citations
30 Claims
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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:
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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 yield strength following manufacture of the coiled steel tube 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification