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Micro-alloying steel for oil gas transport seamless pipeline and its preparation method

A seamless pipeline steel and microalloying technology, applied in the field of metallurgy, can solve the problems of unfavorable HIC performance, lower steel toughness, high Si content, etc., achieve high toughness, good processing performance, eliminate abnormal structure, and meet the requirements of use Effect

Inactive Publication Date: 2008-05-28
LAIWU IRON & STEEL GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The CN1914341 invention patent contains 0.05-1.0% Si, and the high Si content reduces the toughness of the steel, which is not conducive to the further improvement of HIC performance; Ti exists as an inclusion in the steel, and the size of its TiN is less than or equal to 30 μm

Method used

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Examples

Experimental program
Comparison scheme
Effect test

specific Embodiment approach

[0034] The steel of the present invention adopts UHP (ultra-high power) electric furnace + LF (ladle refining) + VD (vacuum degassing) process smelting-continuous casting-heating-750 rolling mill forming-slow cooling process to produce steel. The specific implementation is as follows:

[0035] 1. Chemical composition

[0036] The pipeline steel of the present invention contains the following components. The percentages of alloying elements refer to mass percentages.

[0037] C: 0.08 to 0.20%

[0038] C is an effective element for strengthening steel, and the lower limit of the C content is 0.08% in order to maintain the necessary strength of the pipeline steel. On the other hand, excessive addition of C will increase the hardness of the line pipe, decrease the ductility and weldability, and easily cause SSC. At the same time, the requirements for low-temperature toughness, fracture resistance, ductility and formability of polar pipelines and ocean pipelines have led to a g...

Embodiment 1

[0081] A method for manufacturing pipeline steel, comprising the steps of smelting, refining, continuous casting, hot rolling, and slow cooling, characterized in that:

[0082] 1) Smelting and alloying: electric furnace smelting, slag-free tapping, refining outside the furnace, vacuum degassing treatment until the chemical composition and gas content in the steel meet the requirements, and the hydrogen content in the steel is not more than 2.5×10 -6 , the oxygen content is not more than 25×10 -6 ;

[0083] 2) LF+VD refining, using low-oxygen, low-aluminum clean steel refining technology to ensure deep deoxidation, desulfurization, and full degassing and de-inclusion of molten steel, reduce the content of gas and non-metallic inclusions in steel, and purify steel.

[0084] The low-oxygen, low-aluminum clean steel refining technology adopts known smelting methods, as described on pages 10-13 of "Steelmaking" 2006, Volume 22, No. 2. The difference is:

[0085]In the LF refinin...

Embodiment 2

[0094] Example 2: Physical properties of steel

[0095] According to NACE TM 0177-1996 (American Society of Corrosion Engineers NACE standard), measure the sulfide stress corrosion resistance (SSC) performance of pipeline steel, and measure the HIC resistance CSR (crack sensitivity rate) index of pipeline steel according to NACE TM 0284-1996; The measurement results are shown in Table 3.

[0096] Table 3 Physical properties of steel

[0097] Sample No

[0098] It can be seen from Table 3 that the resistance to sulfide stress corrosion (SSC resistance) and HIC resistance of the pipeline steel of the present invention is significantly better than that of the comparison steel.

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PUM

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Abstract

The invention discloses micro-alloying seamless pipeline steel and process for preparation. According to weight percentage, the range of the chemical components of the invention includes that C holds 0.08% to 0.20%, Si is equal to or less than 0.04%, Mn takes 0.60% to 1. 50%, S is equal to or less than 0.015%, P is equal to or less than 0.025%, Al is equal to or less than 0.04%, Ti is equal to or less than 0.04%, H is equal to or less than 2.5*10-4%, O is equal to or less than 25*10-4%, the rest is Fe and unavoidable foreign matters. The process for preparation comprises technique steps, including smelting, refining, continuous casting, hot rolling and slow cooling. Round steel with the size of phi 70 to 150 millimeters can be produced by the process for preparation. The seamless pipeline steel of the invention has perfect anti-sulphide stress corrosion (SSC resistance) capability and anti-HIC property. The pipeline steel which can substitute for welding pipe can be utilized in the filed of oil pipeline and the like, and the invention increases the reliability of material and adaptability of variety, in particular being adaptable for the low submarine temperature and corrosion-resistant environment and for manufacture of thick-walled tubes.

Description

technical field [0001] The invention relates to the technical field of metallurgy and belongs to the category of pipeline steel. It relates to a microalloyed steel for oil and gas transmission seamless pipelines and a manufacturing method thereof, in particular to a microalloyed steel for manufacturing land and seabed oil and gas transmission pipelines, high-pressure oil and gas gathering and transportation pipelines, high-pressure water injection pipes, and urban pipeline network construction Pipeline steel and method of manufacture thereof. Background technique [0002] In recent years, with the exploration and transportation of deep-sea oil and gas in areas with unstable geological conditions, and long-distance high-pressure oil and gas transportation on land, the development of high-pressure, high-deformation-resistant linepipe steel has become a hot spot for various manufacturers. At present, oil and gas transmission pipelines are developing in the direction of high pe...

Claims

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Application Information

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IPC IPC(8): C22C38/04C22C38/06C22C38/14C22C33/04C21C7/00B22D11/16B21B37/74C21D8/10
Inventor 董杰吉王广连杜显彬张伟翟正龙李猛戈文英王学利郑桂芸
Owner LAIWU IRON & STEEL GRP
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