Extremely-thick low-alloy steel plate with low compression ratio and preparation method thereof

Abstract

The invention relates to an extremely-thick low-alloy steel plate with a low compression ratio. The steel plate is 150-180 mm thick, and consists of the following components in percentage by mass: 0.10-0.17% of C, 0.15-0.45% of Si, 1.18-1.40% of Mn, less than or equal to 0.010% of P, less than or equal to 0.003% of S, 0.10-0.20% of Ni, 0.010-0.040% of Nb and the balance Fe and inevitable impurities; and meanwhile, the content of the corresponding elements meets the following relation: Ceq less than or equal to 0.39%, [C]+[Mn] greater than or equal to 1.35% but less than or equal to 1.50%. A melting process comprises the following steps: oxygen converter smelting, ladle furnace refining, vacuum degassing treatment, continuous casting for slab with thickness being 370 mm or greater, casting blank cover-cooling, casting blank heating, rolling control, cooling control, stacking and slow-cooling, flaw detection and performance examination. The steel plate has the characteristics of being high in strength, excellent in low-temperature toughness, excellent in weldability and the like, and is wider in scope of application.

Description

technical field [0001] The invention belongs to the technical field of low-alloy steel plate smelting, and in particular relates to an extra-thick low-alloy steel plate and its manufacturing method by adopting low compression ratio controlled rolling. Background technique [0002] Extra-thick plates generally refer to steel plates with a thickness ≥ 60mm. Low-alloy extra-thick steel plates are mainly used for large-scale facilities and components that require high steel performance, such as boilers, offshore platforms, bridges, and high-rise buildings. With the rapid development of my country's energy development and infrastructure construction, more and more markets are in urgent need of extra-thick plates, especially some high-performance extra-thick steel plates with a thickness ≥ 150mm. In order to fully ensure the inherent metallurgical quality and core performance of the steel plate , requires the compression ratio of the billet and the steel plate to be ≥ 3, and domest...

AI Technical Summary

Problems solved by technology

[0006] The patent (CN 102009332A) discloses a method for producing extra-thick plates with a stacked rolling welding process, which has a high compression ratio and good internal quality, but it needs to be welded by two or more continuous casting blanks, which is complicated in process, high in cost, and practical Not strong, low yield

[0007] To sum up, when the existing ultra-thick low-alloy steel plates with a thickness of 150-180 mm are produced by die casting, electroslag remelting, and composite slabs, there are problems such as high production costs, long cycle times, and poor practicability; the use of continuous casting slabs During production, there are problems such as low compression ratio and insufficient strength

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