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Grade X80 pipe line steel with low yield ratio and manufacturing method thereof

A technology with low yield ratio and manufacturing method, which is applied in the field of metallurgy, can solve problems such as weak resistance to deformation, and achieve the effects of increasing strength, improving rolling rhythm, and increasing tensile strength

Inactive Publication Date: 2011-09-21
NORTHEASTERN UNIV LIAONING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, X80 pipeline steel (pipeline steel with yield strength ≥ 555MPa) is typical acicular ferrite or bainite. Most of these structures have high strength, but the yield ratio is generally high ( higher than 0.9), so under special geological conditions, the deformation resistance of this high-grade pipeline steel is relatively weak

Method used

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  • Grade X80 pipe line steel with low yield ratio and manufacturing method thereof
  • Grade X80 pipe line steel with low yield ratio and manufacturing method thereof
  • Grade X80 pipe line steel with low yield ratio and manufacturing method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Smelting and pouring into slab according to the set composition, the composition of the slab by weight percentage is: C 0.047%, Si 0.22%, Mn1.89%, S 0.002%, P 0.004%, Al 0.04%, Cu 0.22%, Cr 0.26%, Ni 0.25%, Nb 0.1%, V 0.057%, Ti 0.022%, Mo 0.23%, N 0.0035%, and the rest is Fe.

[0028] Heat the billet to 1180°C and keep it warm for 1h.

[0029] The slab is rolled in two stages, the first rolling temperature is 1150℃, the total reduction is 62.5%; the second rolling temperature is 921℃, the final rolling temperature is 856℃, the second The total reduction of the stage is controlled at 72%.

[0030] After rolling, cool to 710°C at a cooling rate of 80°C / s, air cool for 4 seconds, then cool to 460°C at a cooling rate of 24°C / s; air cool to room temperature.

[0031] The finished product thickness of X80 pipeline steel is 16mm, the yield strength is 585MPa, the tensile strength is 740MPa, the yield strength ratio is 0.790, the elongation after fracture is 18.9%, and the i...

Embodiment 2

[0034] Smelting and pouring into slab according to the set composition, the composition of the slab by weight percentage is C 0.024%, Si 0.24%, Mn1.89%, S 0.002%, P 0.012%, Al 0.035%, Cu 0.22%, Cr 0.08 %, Ni 0.24%, Nb 0.081%, V 0.03%, Ti 0.012%, Mo 0.29%, N 0.003%, Ca 0.0018%, and the rest is Fe.

[0035] Heat the slab to 1200°C and keep it warm for 1.5h.

[0036] The slab is rolled in two stages, the first rolling temperature is 1130℃, the total reduction is 62%; the second rolling temperature is 940℃, the final rolling temperature is 840℃, the second The total reduction of the stage is controlled at 68.4%.

[0037] After rolling, cool to 600°C at a cooling rate of 96°C / s, air cool for 5 seconds, then cool to 490°C at a cooling rate of 18°C / s; air cool to room temperature.

[0038] The finished product thickness of X80 pipeline steel is 12mm, the yield strength is 595MPa, the tensile strength is 745MPa, the yield strength ratio is 0.799, the elongation after fracture is 21....

Embodiment 3

[0041] Smelting and pouring into slab according to the set composition, the composition of the slab by weight percentage is: C 0.06%, Si 0.27%, Mn1.62%, S 0.0019%, P 0.0049%, Al0.045%, Cu 0.15%, Cr 0.11%, Ni 0.25%, Nb 0.072%, V 0.045%, Ti 0.022%, Mo 0.22%, N 0.0043%, and the rest is Fe.

[0042]The billet was heated to 1220°C and kept for 2h.

[0043] The casting billet is rolled in two stages. The first stage rolling temperature is 1100 ° C, and the total reduction is 62%; the second rolling stage rolling temperature is 930 ° C, the final rolling temperature is 845 ° C, and the second rolling The total reduction of the stage is controlled at 68.4%.

[0044] After the rolling is completed, it is cooled to 610°C at a cooling rate of 98°C / s, air-cooled for 18 seconds, and then cooled to 340°C at a cooling rate of 30°C / s; air-cooled to room temperature.

[0045] The thickness of X80 grade pipeline steel is 12mm, the yield strength is 685MPa, the tensile strength is 860MPa, the ...

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Abstract

The invention provides grade X80 pipe line steel with low yield ratio and a manufacturing method thereof, belonging to the technical field of metallurgy; the pipe line steel consists of the following components by weight percent: 0.02-0.06% of C, 0.22-0.29% of Si, 1.6-1.9% of Mn, no greater than 0.002% of S, no greater than 0.012% of P, no greater than 0.045% of Al, 0.15-0.25% of Cu, 0.08-0.26% of Cr, 0.2-0.3% of Ni, 0.07-0.11% of Nb, 0.03-0.057% of V, 0.012-0.022% of Ti, 0.22-0.32% of Mo, no greater than 0.0043% of N, no greater than 0.0018% of Ca and the balance Fe. The manufacturing method comprises the following steps: melting and casting to obtain casting blank; heating and preserving warm; rolling the casting blank in two stages, wherein the start rolling temperature of the first stage of rolling is at 1100-1150 DEG C, the start rolling temperature of the second stage of rolling is at 920-940 DEG C, and the total rolling amount of the second stage is 68.4-72%; and after rolling, quickly cooling the casting blank, cooling the casting blank in the air, and cooling the casting blank to 340-490 DEG C at the cooling speed of 5-30 DEG C / s. The product of this invention has comparatively high strength as well as comparatively low yield ratio, namely excellent large-deformation resistance, can be used for normal transportation and supply of oil gas in earthquake-prone zones and constantly frozen zones, and has wide development prospect.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a low yield ratio X80 grade pipeline steel and a manufacturing method thereof. Background technique [0002] Pipeline transportation is an important way to transport oil and natural gas over long distances. In order to improve the operational efficiency of pipeline transportation and reduce costs, pipeline transportation is developing in the direction of large-caliber and high-pressure transportation. Under the conditions of high pressure and large diameter transportation, more stringent requirements are put forward for the strength, toughness and weldability of materials. [0003] The development trend of oil and natural gas pipelines in the 21st century is mainly reflected in: high-purity steelmaking, high strength and toughness, good welding performance and excellent corrosion resistance; however, with the continuous depletion of energy, pipeline development O...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/58
Inventor 刘振宇周晓光卢敏王国栋吴迪
Owner NORTHEASTERN UNIV LIAONING
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