HEAVY WALL STEEL PIPES WITH EXCELLENT TOUGHNESS AT LOW TEMPERATURE AND SULFIDE STRESS CORROSION CRACKING RESISTANCE
First Claim
Patent Images
1. A heavy wall seamless steel pipe, comprising:
- a steel composition comprising;
about 0.05 wt. % to about 0,16 wt. % carbon;
about 0.20 wt. % to about 0.90 wt. % manganese;
about 0.10 wt. % to about 0.50 wt. % silicon;
about 1.20 wt. % to about 2.60 wt. % chromium;
about 0.05 wt. % to about 0.50 wt. % nickel;
about 0.80 wt. % to about 1.20 wt. % molybdenum;
about 0.005 wt. % to about 0.12 wt. % vanadiumabout 0.008 wt. % to about 0.04 wt. % aluminum;
about 0,0030 wt, % to about 0.0120 wt. % nitrogen; and
about 0.0010 wt. % to about 0.005 wt. % calcium;
wherein the wall thickness of the steel pipe is greater than or equal to 35 mm; and
wherein the steel pipe is processed to have a yield strength greater than or equal to 450 MPa and wherein the microstructure of the steel pipe comprises martensite in a volume percentage greater than or equal to 50% and lower bainite in a volume percentage less than or equal to 50%.
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Accused Products
Abstract
Embodiments of the present disclosure comprise carbon steels and methods of manufacturing thick walled pipes (wall thickness greater than or equal to about 35 mm) there from. In one embodiment, a steel composition is processed that yields an average prior austenite grain size greater than about 15 or 20 μm and smaller than about 100 μm. Using this composition, a quenching sequence is provided that yields a microstructure of greater than or equal to about 50% by volume, and less than or equal to about 50% by volume, lower bainite, without substantial ferrite, upper bainite, or granular bainite. After quenching, pipes may be tempered. The quenched and tempered pipes may exhibit yield strengths greater than about 450 MPa (65 ksi) or 485 (70 ksi). Mechanical property measurements find the quenched and tempered pipes suitable for 450 MPa grade and 485 MPa grade, and resistance to sulfide stress corrosion cracking.
14 Citations
26 Claims
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1. A heavy wall seamless steel pipe, comprising:
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a steel composition comprising; about 0.05 wt. % to about 0,16 wt. % carbon; about 0.20 wt. % to about 0.90 wt. % manganese; about 0.10 wt. % to about 0.50 wt. % silicon; about 1.20 wt. % to about 2.60 wt. % chromium; about 0.05 wt. % to about 0.50 wt. % nickel; about 0.80 wt. % to about 1.20 wt. % molybdenum; about 0.005 wt. % to about 0.12 wt. % vanadium about 0.008 wt. % to about 0.04 wt. % aluminum; about 0,0030 wt, % to about 0.0120 wt. % nitrogen; and about 0.0010 wt. % to about 0.005 wt. % calcium; wherein the wall thickness of the steel pipe is greater than or equal to 35 mm; and wherein the steel pipe is processed to have a yield strength greater than or equal to 450 MPa and wherein the microstructure of the steel pipe comprises martensite in a volume percentage greater than or equal to 50% and lower bainite in a volume percentage less than or equal to 50%. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of making a heavy wall steel pipe, comprising:
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providing a steel having a carbon steel composition; forming the steel into a tube having a wall thickness greater than or equal to 35 mm; heating the formed steel tube in a first heating operation to a temperature within the range between about 900°
C. to about 1060°
C.;quenching the formed steel tube at a rate greater than or equal to 7°
C./sec, wherein the microstructure of the quenched steel is greater than or equal to 50% martensite and less than or equal to 50% lower bainite and wherein the microstructure has an average prior austenite grain size greater than 15 μ
m; andtempering the quenched steel tube at a temperature within the range between about 680°
C. to about 760°
C.;wherein, after tempering, the steel tube has a yield strength greater than 450 MPa and a Charpy V-notch energy greater than or equal to 150 J/cm2 - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification
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Current AssigneeDalmine SPA (Tenaris SA)
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Original AssigneeDalmine SPA (Tenaris SA)
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InventorsAnelli, Ettore, Armengol, Mariano, Novelli, Paolo, Tintori, Federico
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Granted Patent
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Time in Patent OfficeDays
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Field of Search
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US Class Current138/177
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CPC Class CodesC21D 1/18 Hardening C21D1/02 takes pr...C21D 2211/002 BainiteC21D 2211/008 MartensiteC21D 6/002 containing Cr C21D6/004 tak...C21D 8/10 during manufacturing of tub...C21D 8/105 of ferrous alloysC21D 9/085 Cooling or quenchingC22C 38/001 containing NC22C 38/002 containing In, Mg, or other...C22C 38/008 containing tinC22C 38/02 containing siliconC22C 38/04 containing manganeseC22C 38/06 containing aluminiumC22C 38/08 containing nickel C22C38/10...C22C 38/22 with molybdenum or tungstenC22C 38/24 with vanadiumC22C 38/42 with copperC22C 38/44 with molybdenum or tungstenC22C 38/46 with vanadiumC22C 38/60 containing lead, selenium, ...View All
