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CN-122012888-A - Seamless steel tube for ultrahigh-strength and high-toughness drill rod and manufacturing method thereof

CN122012888ACN 122012888 ACN122012888 ACN 122012888ACN-122012888-A

Abstract

The invention provides a seamless steel tube for an ultra-high strength and high toughness drill rod and a manufacturing method thereof, relating to the technical field of ferrous metallurgy, comprising the following manufacturing processes of smelting and producing a continuous casting blank, rolling the continuous casting blank into a round tube blank, rolling the steel tube and performing sample heat treatment; the continuous casting billet is a medium-specification continuous casting square billet, the billet shape is 300mm multiplied by 400mm, and the rolling ratio of the sectional area of the continuous casting billet to the sectional area of the steel pipe obtained after the steel pipe rolling step is more than 20:1. The seamless steel pipe manufactured by the manufacturing method solves the problems of low strength, insufficient toughness, difficult mass production and the like of the existing petroleum drill pipe.

Inventors

  • YAO HUONENG
  • LIU GUANGHUI
  • PENG JUN
  • WAN WUXIA
  • YANG HUANGGUANG
  • XIANG XIN

Assignees

  • 大冶特殊钢有限公司

Dates

Publication Date
20260512
Application Date
20260202

Claims (10)

  1. 1. A method for manufacturing a seamless steel tube for an ultra-high-strength and high-toughness drill rod is characterized by comprising the following manufacturing processes of smelting and producing a continuous casting blank, rolling the continuous casting blank into a round tube blank, rolling the steel tube and performing sample heat treatment; the continuous casting blank is a medium-specification continuous casting square blank, the blank shape is 300mm multiplied by 400mm, and the rolling ratio of the sectional area of the continuous casting blank to the sectional area of the steel pipe obtained after the steel pipe rolling step is more than 20:1.
  2. 2. The method for producing a seamless steel pipe according to claim 1, wherein the seamless steel pipe comprises the following components ：C：0.20%-0.35%,Mn：0.30%-0.45%,Si≤0.40%,P≤0.013%,S≤0.005%,Cr：0.8%-1.30%,Mo：0.80%-1.35%,Ni：0.30%-0.80%,V：0.10%-0.35%、Nb：0.01%-0.05%, by mass percent, the balance being iron and unavoidable impurities.
  3. 3. The method for producing a seamless steel pipe according to claim 1, wherein the outer diameter of the seamless steel pipe is phi 88.9 mm-phi 254mm, the wall thickness is 6.35mm-20mm, and the length is 7m-13.5m; And/or the manufacturing method further comprises the steps of tube blank surface flaw detection, physical and chemical inspection, sawing, ultrasonic flaw detection, finishing, packaging and warehousing, wherein the tube blank surface flaw detection is carried out between the steps of rolling the continuous casting blank into a round tube blank and rolling the steel tube, and the physical and chemical inspection, sawing, ultrasonic flaw detection, finishing, packaging and warehousing are carried out after the sample is subjected to heat treatment.
  4. 4. The method for manufacturing a seamless steel pipe according to claim 1, wherein the specific steps of smelting and producing a continuous casting billet include blast furnace iron making, molten iron desulfurization treatment, converter steelmaking, LF furnace refining, RH vacuum degassing, and continuous casting.
  5. 5. The method for producing a seamless steel pipe according to claim 4, wherein the molten iron desulfurization treatment step is performed with a molten iron S content of 0.005 wt% or less, and the S content after desulfurization is controlled to 0.002% or less wt%; and/or refining time of the LF furnace is more than or equal to 45min; And/or, the RH vacuum degassing time is more than or equal to 20min.
  6. 6. The method for manufacturing the seamless steel tube according to claim 1, wherein the continuous casting billet is rolled into a round tube blank specifically comprises the steps of heating by a stepping furnace, rolling by a high-reduction rolling mill, reducing and sizing by a reducing and sizing mill, wherein the heating temperature of the heating by the stepping furnace is controlled to be 1210-1280 ℃, the soaking time is 90-150 min, the rolling ratio of the continuous casting billet to the round tube billet is more than or equal to 3:1, preferably, the rolling ratio of the continuous casting billet to the intermediate billet obtained after rolling by the high-reduction rolling mill is 1.85:1-2.0:1, and the rolling ratio of the intermediate billet obtained after rolling by the high-reduction rolling mill to the round tube billet obtained after reducing and sizing is 1.8:1-2.1:1.
  7. 7. The method for producing a seamless steel pipe according to claim 1, wherein the steel pipe rolling is performed by heating a pipe blank, piercing by diagonal rolling, jacking a pipe with CPE, and reducing the diameter.
  8. 8. The method for manufacturing a seamless steel pipe according to claim 7, wherein the pipe blank is heated by a ring furnace, the temperature of a soaking section is controlled to be 1200-1280 ℃, and the soaking time is 100-150 min; And/or the CPE jacking pipe adopts a CPE jacking machine to jack the perforated capillary pipe to obtain a pierced billet, the CPE jacking pipe adopts a high-speed jacking mode, the rolling time is less than or equal to 20 seconds, the outer diameter dimension precision is-0.5% D to +1% D, and the wall thickness dimension precision is-5%S to +15% S; And/or the total production time of the cross-rolling perforation and the CPE jacking pipe is 2-4 min.
  9. 9. The method for producing a seamless steel pipe according to claim 1, wherein the sample heat treatment comprises quenching and tempering in this order, wherein the heat-retaining temperature of the quenching is 840 ℃ to 900 ℃, the heat-retaining time is 50min to 90min, the quenching is water-cooled, the heat-retaining temperature of the tempering is 600 ℃ to 640 ℃, the heat-retaining time is 50min to 90min, and the quenching is air-cooled to room temperature.
  10. 10. The seamless steel pipe manufactured by the manufacturing method according to any one of claims 1 to 9, wherein the yield strength of the seamless steel pipe is not less than 1138Mpa, the tensile strength is not less than 1200Mpa, the elongation is not less than 15%, the single minimum value of-20 ℃ longitudinal impact power Kv2 is not less than 100J, and the grain size is 8-11 grades.

Description

Seamless steel tube for ultrahigh-strength and high-toughness drill rod and manufacturing method thereof Technical Field The invention relates to the technical field of ferrous metallurgy, in particular to a seamless steel tube for an ultra-high-strength and high-toughness drill rod and a manufacturing method thereof. Background The drilling tool system for oil and gas exploitation mainly comprises a drilling rod, a weighted drilling rod, a drill collar, a screw drilling tool and a drill bit, wherein the drilling rod is used as an intermediate connecting component and is used for transmitting drilling power and supporting a system, with the progress of oil and gas resource exploration technology, oil and gas exploitation is developed from a ground shallow well with a vertical depth of hundreds of meters to deep wells, ultra-deep wells and deep sea drilling with a depth of thousands of meters, with the increase of drilling depth, the complexity of underground actual working conditions is usually higher than that of earlier exploration prediction, complex geological, high-temperature, high-pressure and corrosive environments are frequently generated, so that the drilling rod is required to be used safely and reliably during deep wells, ultra-deep wells and deep sea drilling operations, enough strength and toughness allowance is reserved in design for resisting overload impact of complex geological layer mutation on the drilling tools, the V150 steel grade with the highest strength in the drilling rod in the API 5DP standard is only greater than 54J, the GB2966 prescribes the U165 grade of the drilling rod with the higher steel grade, and the lowest yield strength is 1138MPa, but the impact strength of the drilling rod with the same requirement for the ultra-deep wells is required to be satisfied only to be equal to the normal temperature J impact and is required to be greater than 54. Patent CN102268609a produced 165 steel grade drill pipe mainly by a two quenching and one tempering process. The patent adopts lower C, mn element content on the steel grade, does not add Nb element, greatly improves the content of V element, and improves the strength of the product by adding alloy element solid solution strengthening and increasing the precipitation strengthening effect of V element. However, since Nb is not added, high-content V (0.1% -0.30%) is added singly for microalloying, grain boundary segregation of V and harmful elements is likely to be caused easily, so that the impact performance is unstable, the highest impact of minus 20 ℃ is only 104J through provided data, the impact allowance is less and can not reach more than 100J, and meanwhile, the drill rod adopts a heat treatment process of quenching after heating at high temperature twice, so that the production efficiency of the product is low. The patent CN103938095B proposes a 165ksi steel-grade high-strength high-toughness drill rod and a manufacturing method thereof, wherein the mass percentage of main active ingredients is C：0.20％-0.40％,Mn：0.50％-1.40％,Cr：0.50％-1.40％,Mo：0.60％-2.10％,Ti：0.005％-0.025％,Nb：0.03％-0.10％,V：0.02％-0.15％,Si：0.20％-0.40％,P≤0.015％,S≤0.008％,[Nb]+[V]+[Ti]≤0.25％,1％≤[Cr]+[Mo]≤3％,, the yield strength of the drill rod can reach 1138MPa (165 ksi), the impact energy at 20 ℃ is more than or equal to 80J, and the provided example data can not reach more than 100J. Meanwhile, the control range of the components C, mn, cr, mo is too wide, the provided examples relate to a plurality of C content components, and the fluctuation of the C content is too large for a drill rod subjected to upsetting treatment at two ends, and the heat treatment process is correspondingly and obviously adjusted, so that the control stability of the heat treatment process is not facilitated. The patent CN108277440B proposes a steel pipe for a drill rod with yield strength larger than 1138MPa and a manufacturing method thereof, wherein the main effective component mass percentage is that the yield strength of the C:0.22%-0.28%、Si:0.15%-0.20%、Mn:0.4%-0.7%、Cr:1.3%-1.6%、Mo:0.7%-1.0%、Ni:1.5%-1.9%、Nb:0.07%-0.15%、S≤0.004%、P≤0.01%, heat-treated steel pipe is 1208 Mpa-1255 MPa (which satisfies 165 KSI), the impact absorption energy under the condition of 20 ℃ is 1101-17J, and the impact absorption energy can all reach more than 100J. However, the patent mainly adds higher Ni element to improve impact toughness, although the aim of greatly improving the impact toughness can be fulfilled, the high Ni steel has larger cracking risk in quenching, is not beneficial to on-site heat treatment control, and meanwhile, in the proposed heat treatment process, water cooling is adopted for tempering, the actual drill rod pipe body is discharged from a furnace for water cooling at 580-620 ℃ provided by the patent, the pipe body is uniformly cooled in the circumferential direction if the pipe body is not rapidly rotated in the water cooling process of the pipe body, the pipe body is extreme