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Method for producing X70 or X80 high-strain steel tube

A technology that resists large deformation and production methods, applied in the direction of pipes, rigid pipes, pipes/pipe joints/fittings, etc., can solve the problem of insufficient understanding of the concept of large deformation pipeline steel, low yield ratio, and failure to consider the forming process. The influence of plasticity, etc., to achieve the effect of excellent longitudinal plastic deformation capacity index, excellent strength and toughness

Active Publication Date: 2012-05-23
BC P INC CHINA NAT PETROLEUM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the X80 large-deformation-resistant pipeline steel produced by this process only considers the two factors of uniform plastic deformation elongation and yield strength ratio, and the concept of large-deformation pipeline steel is not fully understood, so the products produced are not real large-deformation-resistant pipelines steel
Chinese patent 96190145.4 proposes a high-strength pipeline steel with low yield ratio and excellent low-temperature toughness. The pipeline steel produced by this process has a lower yield ratio, but there are still some differences compared with the real large-deformation-resistant pipeline steel. gap
At present, foreign companies have developed X80 large-deformation steel pipes through the UOE process. Chinese patent 200710185346.3 steel pipes produced through the JCOE process only consider the convenience of forming and the strength index meets the requirements of relevant standards, but do not consider the influence of the forming process on the plasticity of steel pipes. and the influence of the coating process on the aging performance and plastic deformation capacity of the steel pipe after the steel pipe is formed, it is not suitable for the production of large deformation resistant steel pipe

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] A continuous casting slab with a thickness of 260mm was selected and kept at 1220°C for 100 minutes. The weight percentage of its chemical composition is: C: 0.060%, Mn: 1.58%, Si: 0.26%, S: 0.0018%, P: 0.012%, Nb: 0.037 %, Ti: 0.024%, V: 0.029%, Mo: 0.18%, Cu: 0.13%, Ni: 0.16%, Cr: 0.024%, limiting elements B: 0.00040%, Ca: 0.005%, N: ≤0.0065%, O: 0.0018%, the rest is iron and unavoidable impurities.

[0026] The continuous casting slab is subjected to two-stage rolling after dephosphorization by high-pressure water. The rolling start temperature in the austenite recrystallization zone is 1180°C, the total deformation of cross rolling is 38%, the deformation of longitudinal rolling is 50%, the final rolling temperature in the austenite recrystallization zone is 1050°C, and the thickness of the intermediate billet is 80mm.

[0027] The intermediate billet is cooled in air and waited until the temperature reaches 900°C to start rolling in the austenite non-recrystallize...

Embodiment 2

[0032] A continuous casting slab with a thickness of 260mm was selected and kept at 1200°C for 120 minutes. The weight percentage of its chemical composition is: C: 0.075%, Mn: 1.78%, Si: 0.20%, S: 0.0019%, P: 0.010%, Nb: 0.048 %, Ti: 0.016%, V: 0.029%, MNi: 0.21%, Cr: 0.20%, limiting elements B: 0.00025%, Ca: 0.006%, N: ≤0.0055%, O: 0.0015%, the rest are iron and non Avoid impurities.

[0033] The continuous casting slab is subjected to two-stage rolling after dephosphorization by high-pressure water. The rolling start temperature in the austenite recrystallization zone is 1170°C, the total deformation of cross rolling is 28%, the deformation of longitudinal rolling is 60%, the final rolling temperature in the austenite recrystallization zone is 1040°C, and the thickness of the intermediate billet is 85mm.

[0034] The intermediate billet is air-cooled and waited until the temperature reaches 910°C to start rolling in the austenite non-recrystallized zone, the compression ra...

Embodiment 3

[0039] Select a continuous casting slab with a thickness of 240mm and hold it at 1200°C for 120min. The weight percentage of its chemical composition is: C: 0.065%, Mn: 1.82%, Si: 0.25%, S: 0.0016%, P: 0.008%, Nb: 0.056 %, Ti: 0.018%, V: 0.022%, Mo: 0.25%, Cu: 0.24%, Ni: 0.21%, Cr: 0.18%, limiting elements B: 0.00035%, Ca: 0.007%, N: ≤0.006%, O: 0.0018%, the rest is iron and unavoidable impurities.

[0040] The continuous casting slab is subjected to two-stage rolling after dephosphorization by high-pressure water. The rolling start temperature in the austenite recrystallization zone is 1180°C, the total deformation of cross rolling is 35%, the total deformation of longitudinal rolling is 50%, the final rolling temperature of austenite recrystallization zone is 1030°C, and the thickness of the intermediate billet is 85mm.

[0041] The intermediate billet is air-cooled and waited until the temperature reaches 920°C to start rolling in the austenite non-recrystallized zone, the...

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Abstract

The invention relates to a method for producing an X70 or X80 high-strain steel tube, which comprises the following steps of: taking following materials by weight percent: 0.035-0.08% of C, 1.55-1.90% of Mn, 0.15-0.3% of Si, less than or equal to 0.0030% of S, less than or equal to 0.0015% of P, 0.025-0.070% of Nb, 0.015-0.035% of Ti, 0.02-0.050% of V, 0.10-0.30% of Mo, 0.10-0.30% of Cu, 0.15-0.35% of Ni, 0-0.30% of Cr, less than or equal to 0.00050% of limiting element B, less than or equal to 0.009% of Ca, less than or equal to 0.008% of N, less than or equal to 0.002% of O, and the balanceof Fe; hot-rolling; air-cooling; performing laminar flow cooling; stamping; expanding; and coating an antiseptic coat. The use requirements of the steel tube in a seismic broken region, a sunken region, a frozen earth region and a landslide region are met.

Description

technical field [0001] The invention relates to a production method of an X70 (transverse yield strength of 485-635 MPa) large-deformation steel pipe or an X80 (transverse yield strength of 555-705 MPa) large-deformation steel pipe. Background technique [0002] In recent years, the changes in the energy structure and the increase in energy demand have greatly promoted the development of long-distance transmission pipelines. In order to improve transmission efficiency and reduce project investment, the steel used for long-distance oil and gas transmission pipelines is constantly developing towards high-grade steel. However, some pipeline projects have to pass through areas with complex geological and geomorphic conditions such as severe cold, landslides, and earthquake zones. Taking the Second West-East Gas Pipeline as an example, the pipeline of the Second West Line passes through a rather long strong earthquake zone and 22 active faults. When disasters such as earthquakes...

Claims

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Application Information

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IPC IPC(8): C22C38/16C22C38/58F16L9/02C21D8/10
Inventor 张伟卫吉玲康陈宏远熊庆人宫少涛罗登熊祥江陈小伟付彦宏
Owner BC P INC CHINA NAT PETROLEUM CORP