Large-strain X80 dual-phase steel plate produced by virtue of process at low temperature and under high pressure

Abstract

The invention belongs to the field of the low-alloy high-strength pipeline steel and more specifically relates to a large-strain X80 dual-phase steel plate produced by virtue of a process at a low temperature and under a high pressure. The large-strain X80 dual-phase steel plate is composed of the following components in percentage by weight: 0.05-0.07% of C, 0.25-0.35% of Si, 1.40-1.80% of Mn, less than or equal to 0.01% of P, less than or equal to 0.003% of S, 0.01-0.04% of Nb, 0.01-0.02% of Ti, less than or equal to 0.035% of Mo, less than or equal to 0.30% of Cu, less than or equal to 0.035% of Cr, less than or equal to 0.030% of Ni, less than or equal to 40ppm of N, less than or equal to 20ppm of O, less than or equal to 1.2ppm of H and the balance of Fe and inevitable impurities. The large-strain X80 dual-phase steel plate has the beneficial effects that the steel plate is subjected to accelerated cooling by virtue of high-pressure water in the adopted rolling process so that the crystalline grain are effectively refined and the production efficiency is improved, and multi-pass cooling and rolling at a low temperature and under high pressure are not carried out in a non-recrystallization zone, and finally, a proeutectoid ferrite-lath bainite structure is obtained, the obtained steel plate has the yield strength Rt0.5 of 480-560MPa, the tensile strength Rm of 770-800MPa, the yield ratio Rt0.5 / Rm being less than or equal to 0.75, the Charpy impact energy at -20 DEG C being greater than or equal to 350J, the drop shear area at -15 DEG C being greater than or equal to 95% and the Uniform elongation UEL being greater than or equal to 12, and the steel plate is high in anti-deforming capability, and furthermore, the stress ratios of the steel plate are as follows: Rt2.0 / Rt1.0 is greater than or equal to 1.09 and Rt1.5 / Rt0.5 is greater than or equal to 1.15.

Description

technical field [0001] The invention belongs to the technical field of low-alloy high-strength pipeline steel manufacturing, and more specifically relates to a large-strain X80 dual-phase steel plate produced by a low-temperature high-reduction process. Background technique [0002] With the rapid development of my country's petroleum and petrochemical industry, in the next period of time, the country will build a large number of new oil pipelines to meet the development needs of the national economy. The more complex, the higher the quality requirements for pipeline steel. As oil and gas pipelines continue to extend to permafrost or earthquake areas, when laying pipelines in these areas, ground movement may cause large strains in steel pipes. Therefore, the pipeline steel used must have the deformation ability to prevent local bending and rupture of pipeline butt girth welds . The way to improve the deformation resistance of steel pipes used in oil and gas pipelines is to ...

AI Technical Summary

Problems solved by technology

The way to improve the deformation resistance of steel pipes for oil and gas pipelines is to increase the wall thickness of the steel pipes, but this will inevitably increase the construction cost of the pipes. The use of steel pipes with large deformation resistance can obtain high deformation resistance of steel pipes without increasing the wall thickness.

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