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X80 level large-deformation resistance pipe line steel medium and heavy plate production method

A technology of anti-large deformation and pipeline steel, applied in workpiece surface treatment equipment, metal rolling, manufacturing tools, etc., can solve the problems of insufficient plasticity and low deformation ability, reduce production costs, and refine austenite grains Effect

Inactive Publication Date: 2009-06-17
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The use of TMCP technology to produce high-strength and high-toughness pipeline steel is basically mature, but the current X80 grade pipeline steel is a typical acicular ferrite or lower bainite structure, and the performance of the steel plate corresponding to this structure type is very good. The strength and toughness match, but its plasticity is insufficient, the uniform deformation elongation UEL≤10%, the yield ratio is mostly above 0.82, and some even exceed 0.90
Therefore, under special geological conditions, the current X80 grade pipeline steel has low deformation resistance caused by stratum displacement.

Method used

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  • X80 level large-deformation resistance pipe line steel medium and heavy plate production method
  • X80 level large-deformation resistance pipe line steel medium and heavy plate production method
  • X80 level large-deformation resistance pipe line steel medium and heavy plate production method

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Experimental program
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Effect test

Embodiment 1

[0032] The molten steel is continuously cast into a billet with a thickness of 230mm, and its chemical composition is calculated by weight percentage: C accounts for 0.037%, Si accounts for 0.20%, Mn accounts for 1.50%, Ti accounts for 0.012%, Ni accounts for 0.22%, Cr accounts for 0.22%, Nb accounts for 0.06%, P accounts for 0.005%, S accounts for 0.003%, H accounts for 0.00018%, N accounts for 0.0015%, O accounts for 0.0013%, and the balance is Fe.

[0033] The billets are soaked at 1200°C and kept for 120 minutes, followed by high-pressure water dephosphorization and two-stage controlled rolling. The starting rolling temperature in the recrystallization zone is 1190°C. After multi-pass rolling, the final rolling temperature in the recrystallization zone is 1040°C, the deformation is 67%, and the thickness of the intermediate billet is 75mm.

[0034] After the intermediate billet is air-cooled and warmed, the rolling start temperature in the non-recrystallized area is 910°C....

Embodiment 2

[0038] The molten steel is continuously cast into a billet with a thickness of 230mm, and its chemical composition is calculated by weight percentage: C accounts for 0.027%, Si accounts for 0.19%, Mn accounts for 1.27%, Ti accounts for 0.012%, Ni accounts for 0.25%, Cr accounts for 0.22%, Nb accounts for 0.06%, P accounts for 0.005%, S accounts for 0.003%, H accounts for 0.00016%, N accounts for 0.0015%, 0 accounts for 0.0015%, and the balance is Fe.

[0039] The billets are soaked at 1200°C and kept for 120 minutes, followed by high-pressure water dephosphorization and two-stage controlled rolling. The starting rolling temperature in the recrystallization zone is 1180°C. After multi-pass rolling, the final rolling temperature in the recrystallization zone is 1030°C, the deformation is 67%, and the thickness of the intermediate billet is 75mm.

[0040] After the intermediate billet is air-cooled and warmed, the rolling start temperature in the non-recrystallized area is 890°C....

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Abstract

The invention relates to a method for producing an X80 grade large deformation resistant pipeline steel medium plate. The economic component design with low carbon is adopted to perform controlling and rolling stages on ingot, namely rolling the grain refined zone and the non grain refined zone. The method comprises: firstly, air cooling and relaxing after finished rolling is performed so that the temperature of a steel plate before entering water and cooled is reduced below the phase change point Ar3 between 30 and 50 DEG C, and 50 to 70 percent of austenite in the relaxing process is converted into proeutectoid ferrite; and secondly, laminar flow cooling is performed on the steel plate within the range of the cooling speed between 20 and 35 DEG C per second, the finished cooling temperature is controlled within the range of between 250 and 400 DEG C; and in the water cooling process, the remaining austenite is converted into bainite structure, and proeutectoid ferrite + bainite double-phase structure is obtained. The intensity and the plasticity index of the finished product satisfy the following requirements: the yield strength Rt0.5 is 530 to 630MPa, the intensity of tension Rm is 625 to 825 MPa, the yield ratio Rt0.5 / Rm is less than or equal to 0.80, and the homogeneous deformation tensile stretch UEL is more than or equal to 10 percent.

Description

technical field [0001] The invention relates to a production technology of medium-thick steel plate for high-strength and high-plasticity pipelines, in particular to a method of adopting low-carbon component design, using air-cooling relaxation + water-cooling to control phase transformation after rolling to obtain a dual-phase structure, and producing X80 grade The invention discloses a manufacturing method of heavy deformation-resistant pipeline steel plate. Background technique [0002] Pipeline transportation is the most economical and reasonable transportation method for oil and natural gas. In order to reduce pipeline construction and operation costs, the transmission pressure and the strength of pipeline steel are constantly increasing. However, simply considering the strength level of pipeline steel can no longer meet the safety requirements of pipeline transportation. The large demand for energy in remote areas makes the construction of ultra-long-distance pipeline...

Claims

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Application Information

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IPC IPC(8): B21B1/22B21B37/74B21B45/02C22C38/50
Inventor 唐荻蔡庆伍武会宾焦多田
Owner UNIV OF SCI & TECH BEIJING
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