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CN-121992314-A - Low-C-high-Mn-Ni-Cu corrosion-resistant L555-level submarine pipeline steel and preparation method thereof

CN121992314ACN 121992314 ACN121992314 ACN 121992314ACN-121992314-A

Abstract

The invention discloses low-C-high-Mn-Ni-Cu corrosion-resistant L555-level submarine pipeline steel and a preparation method thereof, belongs to the technical field of submarine pipeline steel manufacturing, and aims to solve the technical problems of poor corrosion resistance and low-temperature toughness of the existing L555-level submarine pipeline steel. The low-C-high Mn-Ni-Cu corrosion-resistant L555-level submarine pipeline steel provided by the invention comprises the following components in percentage by mass: c: 0.031-0.045%, mn: 2.00-2.10%, si: 0.15-0.22%, ni: 0.60-0.80%, cu: 0.31-0.40%, cr: 0.15-0.20%, nb: 0.020-0.030%, ti: 0.010-0.015%, P is less than or equal to 0.008%, S is less than or equal to 0.002%, N is less than or equal to 0.004%, and the balance is Fe and unavoidable impurities. The L555-level submarine pipeline steel provided by the invention has good corrosion resistance and low-temperature toughness, and is suitable for a main pipe of a deepwater drilling riser and other pressure-bearing service components.

Inventors

  • ZHANG ZHIHUI
  • JIA SHUJUN
  • LIU QINGYOU
  • LI BA
  • WANG BING
  • SUN XINJUN
  • BAI JINPENG

Assignees

  • 钢铁研究总院有限公司

Dates

Publication Date
20260508
Application Date
20260302

Claims (10)

  1. 1. The low-C-high-Mn-Ni-Cu corrosion-resistant L555-level submarine pipeline steel is characterized by comprising the following components in percentage by mass of ：C：0.031-0.045%,Mn：2.00-2.10%,Si：0.15-0.22%,Ni：0.60-0.80%,Cu：0.31-0.40%,Cr：0.15-0.20%,Nb：0.020-0.030%,Ti：0.010-0.015%,P≤0.008%,S≤0.002%,N≤0.004%, balance Fe and unavoidable impurities.
  2. 2. The low C-high Mn-Ni-Cu corrosion resistant grade L555 subsea pipeline steel according to claim 1, comprising by mass percent ：C：0.031-0.04%,Mn：2.00-2.05%,Si：0.15-0.20%,Ni：0.65-0.80%,Cu：0.35-0.40%,Cr：0.18-0.20%,Nb：0.020-0.026%,Ti：0.012-0.015%,P≤0.008%,S≤0.002%,N≤0.004%, balance Fe and unavoidable impurities.
  3. 3. The low C-high Mn-Ni-Cu corrosion resistant grade L555 subsea pipeline steel according to claim 1, wherein the final microstructure of the subsea pipeline steel is based on fine acicular ferrite.
  4. 4. A low C-high Mn-Ni-Cu corrosion resistant grade L555 subsea pipeline steel according to claim 3, wherein the fine acicular ferrite comprises 85-95% of the total volume, accompanied by 5-15% lower or crushed bainite.
  5. 5. A method for preparing the low-C-high-Mn-Ni-Cu corrosion-resistant L555-grade submarine pipeline steel, which is characterized by being used for preparing the low-C-high-Mn-Ni-Cu corrosion-resistant L555-grade submarine pipeline steel according to any one of claims 1 to 5, wherein the preparation method comprises the following steps: Step 1, smelting and continuous casting processes; smelting according to the design components of the L555-level submarine pipeline steel, and adopting converter smelting, LF refining, RH vacuum degassing technology and continuous casting; step2, controlling a rolling process; firstly heating the continuous casting blank to 1180 ℃ plus or minus 10 ℃ and preserving heat for 30-60min, and then sequentially performing rough rolling, intermediate rolling and finish rolling; Step 3, a three-stage temperature control cooling process; the rolled slab is subjected to first-stage rapid cooling, second-stage medium-speed cooling-isothermal holding and third-stage air cooling in sequence; and 4, performing on-line self-tempering treatment on the rolled submarine pipeline steel.
  6. 6. The method for producing a low C-high Mn-Ni-Cu corrosion resistant grade L555 subsea pipeline steel according to claim 5, wherein in step 1, the molten steel temperature is 1600-1650 ℃ and refining time is 15-40 min in the LF refining stage.
  7. 7. The method for producing a low C-high Mn-Ni-Cu corrosion resistant grade L555 subsea pipeline steel according to claim 6, wherein in step 1, the vacuum is 10-50 mbar at 1580-1620 ℃ in the RH vacuum degassing stage.
  8. 8. The method for producing a low C-high Mn-Ni-Cu corrosion resistant grade L555 subsea pipeline steel according to claim 5, wherein in step 2, the rough rolling stage is a stage of rolling a continuous casting billet in a recrystallization zone for 4-6 passes at a finishing temperature of 1050 ℃ + -10 ℃.
  9. 9. The method for producing a low C-high Mn-Ni-Cu corrosion resistant grade L555 subsea pipeline steel according to claim 8, wherein in step 2, the finish rolling stage is a rolling mill billet in the non-recrystallized zone for 4-5 passes.
  10. 10. Process for the preparation of a low C-high Mn-Ni-Cu corrosion resistant grade L555 subsea pipeline steel according to any of claims 5 to 9, characterized in that in step 2 the finishing temperature is 800 ± 10 ℃.

Description

Low-C-high-Mn-Ni-Cu corrosion-resistant L555-level submarine pipeline steel and preparation method thereof Technical Field The invention belongs to the technical field of submarine pipeline steel manufacturing, and particularly relates to low-C-high-Mn-Ni-Cu corrosion-resistant L555-level submarine pipeline steel and a preparation method thereof. Background As the depth of marine oil and gas exploration progresses from shallow sea (< 500 m) to deep sea (> 1500 m), risers are used as key load bearing structures in drilling systems connecting drill floor and blowout preventer, and are in a complex environment of high pressure, low temperature, rich in chloride ions and periodically alternating stress for a long time. The main pipe of the water-proof pipe not only has high yield strength (more than or equal to 550 MPa) and excellent low-temperature toughnessThe impact energy at 40 ℃ is more than or equal to 350J), and stable tissue structure and performance are required to be maintained under various working conditions such as seawater chlorination corrosion, high oxygen content, ocean current impact, welding thermal cycle and the like. The existing L555-level pipeline steel cannot resist long-term electrochemical corrosion of seawater due to poor corrosion resistance and cannot be applied to the pipeline steel due to poor low-temperature toughnessService conditions of 40 ℃ and below. Disclosure of Invention In view of the above analysis, the embodiment of the invention aims to provide low-C-high-Mn-Ni-Cu corrosion-resistant L555-level submarine pipeline steel and a preparation method thereof, which are used for solving the technical problems of poor corrosion resistance and low-temperature toughness of the existing L555-level pipeline steel. The aim of the invention is mainly realized by the following technical scheme: On the one hand, the invention provides low-C-high-Mn-Ni-Cu corrosion-resistant L555-level submarine pipeline steel, which comprises ：C：0.031-0.045%,Mn：2.00-2.10%,Si：0.15-0.22%,Ni：0.60-0.80%,Cu：0.31-0.40%,Cr：0.15-0.20%,Nb：0.020-0.030%,Ti：0.010-0.015%,P≤0.008%,S≤0.002%,N≤0.004%, parts of Fe and unavoidable impurities in percentage by mass. In one possible design, the low C-high Mn-Ni-Cu corrosion resistant L555-grade subsea pipeline steel comprises ：C：0.031-0.04%,Mn：2.00-2.05%,Si：0.15-0.20%,Ni：0.65-0.80%,Cu：0.35-0.40%,Cr：0.18-0.20%,Nb：0.020-0.026%,Ti：0.012-0.015%,P≤0.008%,S≤0.002%,N≤0.004%, balance Fe and unavoidable impurities in mass percent. In one possible design, the final microstructure of the low C-high Mn-Ni-Cu corrosion resistant L555 grade subsea pipeline steel described above is dominated by fine acicular ferrite. In one possible design, the fine acicular ferrite of the low C-high Mn-Ni-Cu corrosion resistant grade L555 subsea pipeline steel described above comprises 85-95% of the total volume, with 5-15% lower or crushed bainite. On the other hand, the invention provides a preparation method of low-C-high-Mn-Ni-Cu corrosion-resistant L555-level submarine pipeline steel, which is used for preparing the low-C-high-Mn-Ni-Cu corrosion-resistant L555-level submarine pipeline steel, and comprises the following steps of: Step 1, smelting and continuous casting processes; Smelting according to the design components of the L555-level submarine pipeline steel, and adopting converter smelting, LF refining, RH vacuum degassing technology and continuous casting; step2, controlling a rolling process; firstly heating the continuous casting blank to 1180 ℃ plus or minus 10 ℃ and preserving heat for 30-60min, and then sequentially performing rough rolling, intermediate rolling and finish rolling; Step 3, a three-stage temperature control cooling process; The rolled slab is subjected to first-stage rapid cooling, second-stage medium-speed cooling and third-stage air cooling in sequence; and 4, performing on-line self-tempering treatment on the rolled submarine pipeline steel. Further, in step 1, in the LF refining stage, the molten steel temperature is 1600-1650 ℃ and the refining time is 15-40 min. Further, in the step 1, in the RH vacuum degassing stage, the continuous casting blank is obtained by performing the steps of vacuum degassing at the molten steel temperature of 1580-1620 ℃ for 10-50 mbar and vacuum degassing time of 8-25 min and repeating the lifting-lowering actions for 1-3 times. Further, in the step 2, the rough rolling stage is to roll the continuous casting blank in 4-6 times in a recrystallization zone, wherein the final rolling temperature is 1050 ℃ plus or minus 10 ℃. Further, in the step 2, after the rough rolling, the rolled blank is rolled for 4-5 times in a non-recrystallization zone, and the final rolling temperature is 800 ℃ plus or minus 10 ℃. Further, in step 4, the steel sheet is subjected to an on-line tempering treatment at 450-480 ℃ for 3-8min after cooling. Compared with the prior art, the invention has at least one of the following beneficial effects: (1) The corrosi