High-strength pipeline steel, steel pipe and manufacture method thereof

Abstract

The invention relates to a high-strength pipeline steel which comprises the following chemical components by weight percent: 0.01-0.12 % of C, 1.0-2.5 % of Mn, less than or equal to 0.6 % of Si, less than or equal to 0.0030 % of S, less than or equal to 0.015 % of P, 0.01-0.09 % of Nb, 0.0025-0.030 % of Ti, less than or equal to 0.08 % of Alt, less than or equal to 1.0 % of Mo, less than or equal to 1.2 % of Cu, less than or equal to 1.5 % of Ni, less than or equal to 1.2 % of Cr, less than or equal to 0.0030 % of B, less than or equal to 0.01 % of Ca, 0.001-0.010 % of N, and the balance being iron and unavoidable impurities. The steel is polygonal ferrite and bainite duplex structure. A manufacture method of the high-strength steel pipe comprises heating slab with a temperature of 1100 to 1250 DEG C, rolling a non-recrystallization region with a starting temperature of 750 to 920 DEG C and a terminating temperature of 720 to 840 DEG C, two-stage cooling under control with an ACC terminating cooling temperature of 200 to 580 DEG C and a cooling rate of 5 to 30 DEG C per second, and manufacturing the pipe by using a UOE technology with a compression rate of 0.1 to 0.5 % and a diameter-expanding rate of 0.5 to 1.5 %. The obtained steel pipe can meet demands of low yield ratio and high uniform elongation.

Description

technical field [0001] The invention relates to pipeline steel, in particular to steel for pipeline steel pipe with low yield ratio, high uniform elongation and high strength, steel pipe and its manufacturing method. Background technique [0002] With the development of the pipeline industry, long-distance oil and gas transportation pipelines need to pass through special areas such as seismic zones and permafrost layers. In order to ensure the safety of pipeline transportation, people have begun to pay attention to the strain resistance of high-strength pipeline steel in recent years. Traditional pipeline design is based on stress design. However, in areas prone to geological disasters such as earthquakes, pipelines will bear large displacement strains, and pipeline failure is not only controlled by stress. For this kind of pipeline engineering, a new concept of "strain-based design" is proposed, and certain strain resistance is required for this kind of pipeline steel. In ...

AI Technical Summary

Problems solved by technology

Traditional pipeline design is based on stress design. However, in areas prone to geological disasters such as earthquakes, pipelines will bear large displacement and strain, and pipeline failure is not only controlled by stress.

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