High-strength toughness low-yield specific heat wide-thick steel plate for bending pipe and production method thereof

Abstract

The invention provides a wide and heavy steel plate for a high-strength high-toughness and low-yield-ratio hot-bending bend and a production method of the wide and heavy steel plate. The steel plate comprises, by weight percentage, 0.055%-0.080% of C, 0.16%-0.30% of Si, 1.76%-1.95% of Mn, 0.051%-0.080% of Nb, 0.010%-0.025% of Ti, 0.09%-0.13% of V, 0.25%-0.45% of Cr, 0.20%-0.35% of Mo, less than 0.25% of Ni, less than 0.25% of Cu, 0.010%-0.035% of Al, not larger than 0.010% of P, not larger than 0.002% of S, 0.001%-0.004% of N and the balance iron and inevitable impurities, wherein (Mo+Ni+Cr+Cu) is controlled within the range of 0.6%-1.0%, CEIIW is controlled within the range of 0.50%-0.55%, and CEPcm is controlled within the range of 0.19%-0.23%. The production method includes the steps ofmolten iron pretreatment, converter smelting, external refining, continuous casting, heating, rolling, cooling and heat treatment. The microstructure of the wide and heavy steel plate is a compositestructure of bainite and ferrite, and the performance meets the requirement of manufacturing X90-grade hot-bending bends with ultra-wide and thick walls in a low-temperature environment.

Description

technical field [0001] The invention belongs to the field of low-carbon and low-alloy steels, and in particular relates to a X90-grade high-strength, high-toughness, low-yield-ratio hot-rolled wide-thick steel plate with a thickness ≥ 22 mm and a width > 4300 mm for hot-simmering pipes in a low-temperature environment and a production method thereof. Background technique [0002] In order to improve the transmission efficiency of oil and gas pipelines, the transmission pressure and pipeline caliber are constantly increasing; in order to take into account the safety of pipeline operation, the corresponding oil and gas pipeline steel is required to develop in the direction of high strength, thick wall, and large plate width. At the same time, as the construction of oil and gas pipelines continues to extend to remote, cold, geologically active areas, and the demand for steel for special environments such as low-temperature stations increases, the low-temperature toughness and...

AI Technical Summary

Problems solved by technology

[0011] The document "The Effect of Whole Heating and Partial Heating on the Microstructure and Properties of X90 High-Strength Steel Hot-simmered Bending Pipe" ("Welded Pipe" 2016, Volume 39, Issue 6, Guo Youtian, Chen Zhongjun, Chen Xuan, etc.), mainly introduces a kind of X90 The influence of the hot-simmering bend and the heat treatment process on it, the composition of the hot-simmering bend is designed with high Mo (>0.40%), the cost of the alloy is high, and the low-temperature toughness is low, and there is a problem of high yield ratio

[0012] In summary, the existing technology is still insufficient in the research on steels for wide-thick and high-strength hot-bending pipes used in low-temperature environments.

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