Methods of manufacturing steel tubes for drilling rods with improved mechanical properties, and rods made by the same
First Claim
1. A method of manufacturing a steel tube, comprising:
- casting a steel having a composition into a bar or slab, the composition comprising;
about 0.18 to about 0.32 wt. % carbon;
about 0.3 to about 1.6 wt. % manganese;
about 0.1 to about 0.6 wt. % silicon;
about 0.005 to about 0.08 wt. % aluminum;
about 0.2 to about 1.5 wt. % chromium;
about 0.2 to about 1.0 wt. % molybdenum; and
the balance comprises iron and impurities;
wherein the amount of each element is provided based upon the total weight of the steel composition;
forming a tube;
quenching the tube from an austenitic temperature to form a quenched tube;
cold drawing the quenched tube to form a final tube; and
tempering the final tube to form the steel tube.
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Accused Products
Abstract
Embodiments of the present disclosure are directed to methods of manufacturing steel tubes that can be used for mining exploration, and rods made by the same. Embodiments of the methods include a quenching of steel tubes from an austenitic temperature prior to a cold drawing, thereby increasing mechanical properties within the steel tube, such as yield strength, impact toughness, hardness, and abrasion resistance. Embodiments of the methods reduce the manufacturing step of quenching and tempering ends of a steel tube to compensate for wall thinning during threading operations. Embodiments of the methods also tighten dimensional tolerances and reduce residual stresses within steel tubes.
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Citations
26 Claims
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1. A method of manufacturing a steel tube, comprising:
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casting a steel having a composition into a bar or slab, the composition comprising; about 0.18 to about 0.32 wt. % carbon; about 0.3 to about 1.6 wt. % manganese; about 0.1 to about 0.6 wt. % silicon; about 0.005 to about 0.08 wt. % aluminum; about 0.2 to about 1.5 wt. % chromium; about 0.2 to about 1.0 wt. % molybdenum; and the balance comprises iron and impurities; wherein the amount of each element is provided based upon the total weight of the steel composition; forming a tube; quenching the tube from an austenitic temperature to form a quenched tube; cold drawing the quenched tube to form a final tube; and tempering the final tube to form the steel tube. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of manufacturing a steel tube for use as a drilling rod for wireline systems, comprising:
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casting a steel having a composition into a bar or slab, the composition comprising; about 0.2 to about 0.3 wt. % carbon; about 0.3 to about 0.8 wt. % manganese; about 0.1 to about 0.6 wt. % silicon; about 0.8 to about 1.2 wt. % chromium; about 0.25 to about 0.95 wt. % molybdenum; about 0.01 to about 0.04 wt. % niobium; about 0.004 to about 0.03 wt. % titanium; about 0.005 to about 0.080 wt. % aluminum; about 0.0004 to about 0.003 wt. % boron; up to about 0.006 wt. % sulfur; up to about 0.03 wt. % phosphorus; up to about 0.3 wt. % nickel; up to about 0.02 wt. % vanadium; up to about 0.02 wt. % nitrogen; up to about 0.008 wt. % calcium; up to about 0.3 wt. % copper; and the balance comprises iron and impurities; wherein the amount of each element is provided based upon the total weight of the steel composition; forming a tube; cooling the tube to about room temperature; cold drawing the tube in a first cold drawing operation to effect an about 15% to about 30% area reduction and form a tube with an outer diameter between about 38 mm and about 144 mm and an inner diameter between about 25 mm and about 130 mm; heat treating the tube according to a first heat treatment operation to an austenizing temperature between about 50°
C. above AC3 and less than about 150°
C. above AC3 following by quenching to about room temperature at a minimum of 20°
C./second;cold drawing the quenched tube in a second cold drawing operation to effect an area reduction of about 6% to about 14% to form a tube with an outer diameter of about 34 mm to about 140 mm and an inner diameter of about 25 mm to about 130 mm; heat treating the tube in a second heat treatment operation to a temperature of about 400°
C. to about 600°
C. for about 15 minutes to about one hour to provide stress relief to the tube; andcooling the tube after the second heat treatment operation to about room temperature at a rate of between about 0.2°
C./second and about 0.7°
C./second;wherein the final steel tube after the second heat treatment operation has a microstructure of about 90% or more tempered martensite, an average grain size of about ASTM 7 or finer, a yield strength above about 930 MPa, an ultimate tensile strength above about 965 MPa, elongation above about 13%, hardness between about 30 and about 40 HRC, an impact toughness above about 30J in the longitudinal direction at room temperature based on a 10×
3.3 mm sample, and residual stresses of less than about 150 MPa. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method of manufacturing a wireline system steel tube drilling rod having tight dimensional tolerances for outer diameter, inner diameter, concentricity, and straightness, the method comprising:
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casting a steel having a composition into a bar or slab, the composition comprising; about 0.18 to about 0.32 wt. % carbon; about 0.3 to about 1.6 wt. % manganese; about 0.1 to about 0.6 wt. % silicon; about 0.005 to about 0.08 wt. % aluminum; about 0.2 to about 1.5 wt. % chromium; about 0.2 to about 1.0 wt. % molybdenum; and the balance comprises iron and impurities; wherein the amount of each element is provided based upon the total weight of the steel composition; forming a tube; quenching the tube from an austenitic temperature to form a quenched tube; cold drawing the quenched tube to form a final tube with a maximum area reduction of about 30%; tempering the final tube to form the steel tube; and straightening the tempered tube. - View Dependent Claims (26)
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Specification