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CN-122013045-A - Low-temperature toughness stable control thin-specification pipeline steel plate based on strain design and manufacturing method thereof

CN122013045ACN 122013045 ACN122013045 ACN 122013045ACN-122013045-A

Abstract

The invention discloses a low-temperature toughness stable control thin-specification pipeline steel plate based on strain design and a manufacturing method thereof, and belongs to the technical field of low-carbon microalloy steel production. The method comprises the steps of molten steel smelting, external refining (LF refining), RH vacuum degassing, continuous casting, casting blank heating, controlled rolling, relaxation, heat supplementing of an incubator and cooling, and air cooling to room temperature. The invention realizes the stable control of the low-temperature toughness of the L450M pipeline steel plate for the gas pipeline with the pipe diameter of less than phi 1016mm based on strain design, which is used for rolling thin gauge (9-13 mm).

Inventors

  • XU HAIJIAN
  • TIAN HONGXIN
  • HAN CHUFEI
  • MA JUN
  • SHU YIBO

Assignees

  • 鞍钢股份有限公司

Dates

Publication Date
20260512
Application Date
20260312

Claims (10)

  1. 1. A low-temperature toughness stable control thin-specification pipeline steel plate based on strain design is characterized in that the chemical components of the steel plate are ：C 0.05%～0.08%,Si 0.15%～0.25%,Mn 1.48%～1.58%,P≤0.020%,S≤0.015%,Nb 0.02%～0.04%, Ti 0.008%～0.020%,Al 0.015%～0.04%,Cr 0.10%～0.20%,Mo 0.04%～0.09%,Ni 0.1%～0.12%,N 0.003％～0.006％, weight percent of Fe and unavoidable impurities in balance.
  2. 2. The strain design-based thin gauge pipeline steel sheet with stable control of low temperature toughness of claim 1, wherein the steel sheet has a thickness of 9-13 mm.
  3. 3. The strain design-based low temperature toughness stability controlled thin gauge steel sheet of claim 1 used to fabricate gas lines having a pipe diameter of Φ1016mm or less.
  4. 4. The strain design-based thin gauge pipeline steel sheet with stable control of low temperature toughness according to claim 1, wherein the steel sheet has a yield strength of 450-520 mpa in transverse stretching, a tensile strength of 560-620 mpa, a yield ratio of less than 0.85, an elongation of not less than 25%, a transverse Charpy impact power of not less than 150J at-40 ℃, a transverse shear area steel sheet head-middle-tail positions SA of not less than 90%, and a longitudinal uniform elongation of not less than 10%.
  5. 5. The method for manufacturing a low-temperature toughness stability controlled thin gauge pipeline steel sheet based on strain design as set forth in any one of claims 1 to 4, comprising the steps of: 1) Molten steel smelting and continuous casting, namely, carrying out pretreatment, converter smelting, LF refining, RH vacuum degassing and continuous casting on molten iron, wherein the superheat degree of continuous casting is 8-13 ℃, the continuous casting billet drawing speed is 0.8-1.1 m/min, the pressing amount of a solidification tail end is 16-20 mm under the heavy pressing, and the casting billets after offline are stacked and slowly cooled, the stacking temperature is not lower than 700 ℃, and the slow cooling time is not lower than 48 hours; 2) Heating the casting blank, namely, feeding the casting blank into a heating furnace for heating, and discharging the casting blank from the furnace after sequentially passing through a preheating section, a heating section and a soaking section, wherein the temperature of the preheating section is 750-900 ℃, the temperature of the heating section is 1190-1200 ℃, the temperature of the soaking section is 1160-1175 ℃, the total furnace time of the heating section and the soaking section is controlled to be 2.0-3.0 hours, and the temperature difference between the upper surface and the lower surface of the casting blank is ensured to be within 15 ℃; 3) The high-pressure water descaling and controlled rolling, namely, descaling a casting blank after tapping by using high-pressure water for 1-2 min before starting rolling, wherein the pressure of a descaler is 15-25 MPa, a rolling mode of transverse and longitudinal rolling is adopted, the rolling reduction rate of each pass of two passes before rolling is more than 25% in a transverse rolling stage, the rolling reduction rate of each pass of three passes before rolling is more than 20% in a longitudinal rolling stage, the rolling reduction rate of each pass of the three passes before rolling is less than 5% in a final pass, and the final rolling temperature of a steel plate is 780-830 ℃; 4) Relaxation, heat-supplementing and cooling of an incubator, namely, after rolling, carrying out relaxation to be warm on a steel plate, carrying out pre-straightening input at 680-690 ℃, leading the steel plate into a roller position of-1.0 mm to-1.5 mm, leading the steel plate out of a roller position of-2.0 mm to-2.5 mm, and enabling straightening force to be 800 KN-1100 KN, then carrying out heat-supplementing on the steel plate in the incubator, enabling the steel plate to pass through the incubator at a speed of 0.3-0.5 m/s and a temperature of 650-660 ℃, then adopting laminar cooling, enabling the cooling temperature to be 640-650 ℃, enabling the final cooling temperature to be 405-425 ℃, controlling the cooling speed to be 10-15 ℃ per s, enabling the steel plate to be opened at a side spraying pressure and a wind blowing pressure after the steel plate is discharged and opened, and enabling the side spraying pressure and the water quantity to be 5-10 MPa and 50-100 m 3 /h respectively, and enabling the wind blowing pressure to be 5-10 MPa; 5) Air-cooling to room temperature.
  6. 6. The method according to claim 5, wherein in step 1), the raw materials are pretreated by KR molten iron, the S content is controlled to be lower than 0.015%, slag is removed, the raw materials enter a converter, the P content is controlled to be less than or equal to 0.02% during converter smelting, the C content is controlled to be 0.05% -0.08% during converter smelting end point control, argon is blown for 20-30 min during tapping, LF refining and RH vacuum degassing are carried out, RH vacuum is maintained for more than 30min, and continuous casting is carried out.
  7. 7. The method according to claim 6, wherein the double slag method is used for removing P in the converter smelting process.
  8. 8. The method according to claim 5, wherein the thickness of the cast slab is 135 to 170mm.
  9. 9. The method according to claim 5, wherein in the step 4), the number of the opening groups of the cooling control header is 3-6 groups, and the water amount of the single header is 155-180 m 3 /h.
  10. 10. The method according to claim 5, wherein the steel sheet is produced on a heavy and medium plate reciprocating mill using a cast slab, and the cooling medium is water.

Description

Low-temperature toughness stable control thin-specification pipeline steel plate based on strain design and manufacturing method thereof Technical Field The invention belongs to the technical field of low-carbon microalloyed steel production, and particularly relates to an L450M steel plate for an oil-gas pipeline, which has a thickness specification of 9-13 mm and a pipe diameter of less than phi 1016mm and is based on strain design and is used for stably controlling low-temperature toughness, and a manufacturing method thereof. Background In recent years, energy source conveying pipeline construction is rapidly developed, and the toughness requirements on the selected steel raw materials are higher and higher in order to improve the conveying efficiency and the operation safety. At present, the major pipeline main line at home and abroad basically adopts an L485M, L M steel grade, and branch lines, urban pipe networks and the like are mostly selected from L450M steel grades with thin specifications (9-13 mm) and small calibers (phi 1016mm or below). When the pipeline region is in an extremely cold zone or an earthquake crossing zone, higher requirements are put forward on indexes such as low-temperature toughness, plastic deformation capacity and the like of raw materials from the aspects of operation stability and safety, for example, the low-temperature drop hammer, the temperature required for ductile-brittle transition temperature test is lower, the value of Charpy impact power requirement is higher, and meanwhile, the severe requirements are put forward on the longitudinal uniform elongation of the steel pipe, so that higher personalized requirements are put forward in the projects, and only the API SPEC 5L specification is met, but is far from enough. In addition, in the face of severe market situation, user requirements and manufacturing cost pressure in the steel industry, alloy and energy costs are reduced while the product quality is ensured, so that the production line reduces resource consumption as much as possible, and the method is particularly important. L450M pipeline steel is generally produced by adopting a two-stage controlled rolling process, meanwhile, in order to ensure the accumulated rolling reduction rate in the finish rolling stage and static recrystallization of an intermediate billet, the thick waiting temperature of the intermediate billet needs to be maintained, so that the waiting temperature of the intermediate billet is longer, the final rolling temperature can be controlled below 850 ℃ or even lower, and the rolling difficulty is greatly increased. Firstly, the rolling mill load, the longitudinal temperature difference between the head and the middle and the tail of the thin steel plate, the structure and the performance uniformity, the shape control and the like are all subjected to serious test, and secondly, the improvement of the steel plate performance mainly depends on the content of impurities such as phosphorus and sulfur in the steel, the content of alloy elements in the steel and the control of key technological parameters in the production processes such as smelting, rolling and the like. Therefore, how to solve the problems existing in the production of the strain-design-based thin L450M pipeline steel plate and realize the low-temperature toughness stable control of the strain-design-based thin L450M pipeline steel plate is a key point for the development of the thin-specification strain-design-based L450M pipeline steel. Compared with the prior art: So far, the low-temperature toughness report of the L450M pipeline steel plate with the thin specification for stably controlling the strain design at home and abroad is very little. Prior to the present invention, application number CN201010243241.0 discloses an X65 pipeline steel and a method for producing the same. The weight percentage of the components of the patent is C 0.055％～0.090％、Si 0.15％～0.35％、Mn 1.50％～1.65％、P≤0.020％、S≤0.005％、Nb 0.040％～0.055％、V 0.040％～0.070％、Ti 0.010％～0.025％、N≤0.008％、Als 0.005％～0.060％., the components of the steel type contain higher V, natural air cooling is adopted in the process, the efficiency is low, the effects of reducing the cost and improving the toughness of the alloy can not be fully exerted, in addition, the specific toughness and plastic deformation indexes of the physical object of the product are not defined, and the stability control index of the low-temperature toughness of the steel plate is not defined. Application number CN201110179945.0 discloses an X65 pipeline steel excellent in low-temperature toughness and a manufacturing method thereof. The weight percentage of the components in the patent is C 0.020％～0.055％、Si 0.10％～0.25％、Mn 1.50％～1.70％、Nb 0.060％～0.080％、Cr 0.20％～0.35％、V 0.020％～0.040％、Ti 0.010％～0.020％、Als 0.010％～0.040％、P≤0.018％、S≤0.005％、N≤0.006％., the steel contains V, the alloy cost is high, laminar cooling is adopted in the process, the effects of reducing