550 MPa-grade low-compression-ratio high-toughness steel plate for ocean engineering platform and production method

Abstract

The invention belongs to the technical field of steel materials, and relates to a 550 MPa-grade low-compression-ratio high-toughness steel plate for an ocean engineering platform and a production method, in particular to a steel plate with high strength and toughness under conditions of the low carbon content and the low compression ratio for ocean engineering and the production method. The steel plate comprises chemical components in percentage by weight as follows: 0.04-0.10% of C, 0.2-0.4% of Si, 1.0-1.5% of Mn, smaller than 0.010% of P, smaller than 0.003% of S, 0.5-0.8% of Ni, 0.2-0.5% of Cu, 0.30-0.80% of Cr, 0.1-0.3% of Mo, 0.02-0.05% of Nb, 0.010-0.025% of Ti and the balance of Fe and inevitable impurities. The alloy C is low in content, and welding is easy. Under the condition that the thickness of a casting blank is only 250 mm, the content of the C, the P and the S is controlled strictly, the temperature is decreased and then increased, the TMCP process is optimized, the rolling temperature is decreased, the reduction at rough rolling and finish rolling stages is distributed reasonably, the cooling process and the tempering heat treatment temperature are optimized, and steel can have high strength and high low-temperature toughness under the condition of the low compression ratio (the minimum is only 3.125:1).

Description

technical field [0001] The invention belongs to the technical field of iron and steel materials, and relates to a 550MPa low-compression-ratio high-toughness steel plate for marine engineering and a production method, in particular to a steel plate for marine engineering that realizes high strength and high toughness under conditions of low carbon content and low compression ratio and production methods. Background technique [0002] Marine rights and interests are one of the core interests of our country. In recent years, the implementation of the national marine strategy has made marine engineering the focus of construction and development, and has gradually developed from the offshore to the deep sea. The rapid development of the ocean engineering equipment industry will create a huge demand for steel for ocean engineering, especially with the large-scale, high-parameterization, and lightweight of ships, ocean engineering, port machinery, and submarine oil pipelines, the ...

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Problems solved by technology

Among them, since the method of normalizing usually obtains ferrite plus pearlite structure, the strength is not easy to increase, and it is mainly used to produce marine steel products below 420MPa; while the method of controlled rolling and controlled cooling can obtain high strength, but due to the The thickness is relatively large, and it is difficult to achieve a large reduction in the rolling stage, especially the structure refinement of the core in the rough rolling stage and the austenite deformation in the finishing rolling stage are difficult to guarantee. To ensure toughness under this condition, it is necessary to Larger compression ratio; and the production method of quenching and tempering can improve the strength while ensuring toughness, but compared with the production method of controlled rolling and controlled cooling, when producing steel with the same strength level, the quenching and tempering process needs to be added More alloying elements to ensure strength, which not only leads to cost increase, but also is not conducive to welding, and the cost of quenching and tempering heat treatment process is relatively high

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