High strength steel pipes with excellent toughness at low temperature and sulfide stress corrosion cracking resistance
First Claim
Patent Images
1. A seamless steel pipe, comprising:
- a steel composition comprising;
Fe;
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 8 mm and less than or equal to 35 mm;
wherein the steel pipe is processed to have a yield strength greater than 550 MPa (80 ksi) and wherein the microstructure of the steel pipe comprises martensite in a volume percentage greater than or equal to 60% and lower bainite in a volume percentage less than or equal to 40%;
wherein the microstructure of the steel pipe does not include upper bainite nor ferrite;
wherein the steel pipe has a ductile to brittle transition temperature less than −
70°
C.; and
wherein the steel pipe does not exhibit failure due at least in part to stress corrosion cracking after about 720 hours when subjected to a stress of about 90% of the yield stress and tested according to National Association of Corrosion Engineers standard TM0177.
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Accused Products
Abstract
Low-alloy steels and methods of manufacturing pipes having a wall thickness greater than or equal to about 8 mm and less than or equal to about 35 mm therefrom are provided. 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. A quenching sequence has been determined that yields a microstructure of greater than or equal to about 60% martensite by volume, and less than or equal to about 40% by volume lower bainite, without substantial formation of ferrite, upper bainite, or granular bainite. The yield strength of the quenched and tempered pipes may be greater than about 70 ksi, 80 ksi, or 90 ksi. The quenched and tempered pipes are suitable for 70 ksi, 80 ksi, and 90 ksi grades and resistant to sulfide stress corrosion cracking.
143 Citations
13 Claims
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1. A seamless steel pipe, comprising:
-
a steel composition comprising; Fe; 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 8 mm and less than or equal to 35 mm; wherein the steel pipe is processed to have a yield strength greater than 550 MPa (80 ksi) and wherein the microstructure of the steel pipe comprises martensite in a volume percentage greater than or equal to 60% and lower bainite in a volume percentage less than or equal to 40%; wherein the microstructure of the steel pipe does not include upper bainite nor ferrite; wherein the steel pipe has a ductile to brittle transition temperature less than −
70°
C.; andwherein the steel pipe does not exhibit failure due at least in part to stress corrosion cracking after about 720 hours when subjected to a stress of about 90% of the yield stress and tested according to National Association of Corrosion Engineers standard TM0177. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A 550 MPa (80 ksi) grade seamless steel pipe, comprising:
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Fe; about 0.10 wt. % to about 0.13 wt. % carbon; about 0.40 wt. % to about 0.55 wt. % manganese; about 0.20 wt. % to about 0.35 wt. % silicon; 2.1 wt. % to about 2.6 wt. % chromium; about 0.9 wt. % to about 1.10 wt. % molybdenum; about 0.001 wt. % to about 0.005 wt. % calcium; about 0.050 wt. % to about 0.07 wt. % vanadium; about 0.010 wt. % to about 0.020 wt. % aluminum; wherein a wall thickness of the steel pipe is greater than or equal to 8 mm and less than or equal to 35 mm; and wherein the steel pipe is processed by; hot rolling followed by cooling to room temperature, heating to a temperature of about 900°
C. or above,quenching at a cooling rate greater than or equal to 40°
C./sec, andtempering at a temperature between 680°
C. to 760°
C.,wherein the processed steel pipe has a microstructure comprising a prior austenite grain size of about 20 μ
m to about 80 μ
m, a packet size of about 3 μ
m to about 6 μ
m, about 90% martensite by volume or greater, and about 10% lower bainite by volume or less, wherein the microstructure does not include ferrite; andwherein the steel pipe has a yield strength (YS) between about 550 MPa (80 ksi) and about 705 MPa (102 ksi), an ultimate tensile strength (UTS) between about 625 MPa (90 ksi) and about 825 MPa (120 ksi), elongation no less than about 20%, and a YS/UTS ratio no higher than about 0.93.
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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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Primary Examiner(s)Yang, Jie
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Application NumberUS13/367,332Publication NumberTime in Patent Office1,870 DaysField of Search148/593, 148/335US Class Current1/1CPC 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 9/08 for tubular bodies or pipesC21D 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 vanadiumView All
