Preparation method and application of x80m pipeline steel resistant to low temperature and large strain

Abstract

The invention relates to X80M pipeline steel resistant to low temperature and large in strain and a manufacturing method and application of the X80M pipeline steel. The X80M pipeline steel is composed of, by weight, 0.03% to 0.07% of C, 0.15% to 0.35% of Si, 1.50 % to 2.00% of Mn, not larger than 0.009% of P, not larger than 0.002% of S, 0.06% to 0.09% of Nb, 0.015% to 0.020% of Ti, 0.015% to 0.025% of Zr, not larger than 0.30% 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. The heating temperature is strictly controlled for implementing low-temperature heating, the grain size is prevented from being increased, and through the reasonable match of a recrystallization deformation temperature section in a rough rolling stage, the rolling reduction of the last pass of rough rolling and the temperature, the austenite grain size is reduced to the maximum degree; and a large accumulated deformation rolling technical measure is adopted in non-recrystallization region deformation in a finish rolling stage, the effect that the phase change is induced through strain is used, a large amount of fine proeutectoid ferrite is generated through low-temperature rolling deformation induction, starting cooling temperature is accurately controlled, and a ferrite and bainite double-phase structure is formed.

Description

technical field [0001] The invention belongs to the field of low-alloy structural steel, and in particular relates to a low-temperature-resistant and large-strain X80M pipeline steel and a preparation method and application thereof. Background technique [0002] In recent years, with the continuous growth of energy demand, resources such as oil and natural gas in alpine regions have gradually begun to be developed. Pipelines transporting oil and gas from such regions pass through cold, unstable terrain. In such areas, thick gauge steel pipes with good low temperature toughness and high strain capacity are required. In order to achieve the above purpose, in the production process of X80M pipeline steel with low temperature resistance and large strain thickness, it is necessary to ensure low temperature heating under the condition of solid solution of microalloying elements, so as to avoid the growth of austenite grain size and the recrystallization zone of the steel plate. ...

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Problems solved by technology

[0003] In the Chinese patent application CN103981462A published on August 13, 2014, a large-wall thickness X80 low-temperature station steel with excellent toughness and its manufacturing method are described. The steel plate structure is mainly acicular ferrite structure, and the steel plate The strength ratio is high, and it does not have the ability of large strain

[0007] In the Chinese patent application CN103103449A published on May 15, 2013, a large deformation-resistant X80 pipeline steel and its production method are recorded. It does not mention the specifications of the steel plate, and the finishing rolling temperature is not controlled in the rough rolling stage of the production process. At the lower limit of the deformation temperature, and the intermediate billet is not cooled after the end, 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 and the cooling rate is high. Compared with air cooling, the production is unstable.

[0008] The Chinese patent authorization CN101456034B published on February 16, 2011 describes a method for producing medium-thick plates of X80-grade large-deformation-resistant pipeline steel. The thickness of the steel plates is only 12mm, and the specifications are limited. More than 5 times, not applicable to thick gauge pipeline steel

In terms of refining the grain size of the steel plate, the patent did not effectively control the deformation temperature of the pass in the rough rolling process, and did not carry out deformation-induced phase change rolling in the finishing rolling stage, and at the same time, the temperature of the steel plate drop weight test only met -15°C Environment, not suitable for -25°C and low temperature environment below this temperature

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