A kind of x80 pipeline steel with high stress ratio and high crack arrest toughness and its preparation method and application

Abstract

The invention specifically relates to X80 pipeline steel with the high stress ratio and high arrest toughness and a preparation method and application of the X80 pipeline steel. The X80 pipeline steel is composed of, by weight, 0.03% to 0.08% of C, 0.15% to 0.35% of Si, 1.50% to 2.00% of Mn, not larger than 0.010% of P, not larger than 0.003% of S, 0.04% to 0.08% of Nb, 0.015% to 0.025% of Ti, 0.015% to 0.025% of Zr, not larger than 0.03% of Mo, not larger than 0.35% of Cu, not larger than 0.30% of Ni, not larger than 0.30% of Cr and the balance Fe and inevitable impurities. Zirconium is added to promote precipitation of proeutectoid ferrite, the banded structure level is reduced, and the stress ratio and the arrest toughness of a steel plate are effectively improved. The heating temperature is strictly controlled, and the recrystallization deformation temperature section in a rough rolling stage and the rolling reduction and the temperature of the last phase of rough rolling are reasonably matched, so that the austenite grain size is reduced to the maximum degree; and a rough-rolled intermediate billet is cooled, so that grain growth generated after recrystallization deformation is reduced.

Description

technical field [0001] The invention belongs to the field of low-alloy structural steel, and in particular relates to an X80 pipeline steel with high stress ratio and high crack arrest toughness, a preparation method and application thereof. Background technique [0002] With the continuous growth of energy demand in recent years, most of the pipelines transporting oil and gas have to pass through cold and unstable terrain areas. In such areas, steel pipes with high deformability and high crack arrest toughness are required. In order to achieve the above purpose, in the production process of X80M pipeline steel, it is necessary to ensure the austenite grain refinement effect of rolling in the recrystallization zone of the steel plate, the rolling at low temperature and high pressure in the non-recrystallization zone, and the accurate control after rolling cooling technology. In this way, the steel plate with fine grain and multi-phase structure can be produced, and the cha...

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Problems solved by technology

[0005] The Chinese patent application CN103131833A published on June 5, 2013 describes a method for obtaining X80M steel grade dual-phase structure large-strain pipeline steel. The process parameters are obtained in the laboratory, which is quite different from industrial on-site production.

[0006] In the Chinese patent application CN103103449A published on May 15, 2013, a large deformation-resistant X80M pipeline steel and its production method are described. The rough rolling stage in the production process does not control the final rolling temperature at the lower limit of the deformation temperature, and After the end, the temperature of the intermediate billet is not cooled, and the growth of the grain size cannot be effectively prevented

In addition, this document adopts two-stage cooling after finishing rolling, the temperature drop range of the first stage cooling is small, the cooling rate is high, and it is difficult to control during production

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