Production method of EH420-grade 150 to 200mm extra-thick steel plate

Abstract

The invention discloses a production method of an EH420 grade 150 to 200mm extra-thick steel plate, and relates to the technical field of ocean engineering steel. The steel plate comprises the chemical components of, by mass, 0.10% to 0.14% of C, 0.20% to 0.50% of Si, 1.00% to 1.45% of mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.030% to 0.080% of Nb, 0.001% to 0.050% of V, 0.01% to 0.05% of Al, 0.005% to 0.020% of Ti, 0.15% to 0.35% of Cr, 0.10% to 0.50% of Cu, 0.01% to 0.80% of Ni, and the balance of Fe and inevitable impurities, wherein Cr+Ni+Cu is less than or equal to 1.30%.

Description

technical field [0001] The invention relates to the technical field of steel for marine engineering, in particular to a production method of EH420 grade 150-200mm extra-thick steel plate. Background technique [0002] With the gradual implementation of the national marine economic strategy, the steel used in marine engineering is developing in the direction of ultra-high strength and extra-thickness, and higher and higher requirements are put forward for the performance and quality of extra-thick steel plates. [0003] The greater the thickness of the extra-thick steel plate, the more severe the adverse effect on the performance caused by the segregation of the central composition of the slab. Due to the different cooling rates in the thickness direction, there are great differences in the structure, and the performance of the core is difficult to meet the certification specifications of the classification society, resulting in unqualified products. The deformation is uneve...

AI Technical Summary

Problems solved by technology

Due to the different cooling rates in the thickness direction, there are great differences in the structure, and the performance of the core is difficult to meet the classification society certification specifications, resulting in unqualified products

The deformation is uneven during the rolling process, and it is difficult to eliminate various defects caused by the billet, which seriously affects the low-temperature impact toughness of the steel plate, especially the low-temperature toughness of the core

[0004] In order to ensure the low temperature toughness of the core, the conventional process requires the thickness of the billet to be more than 3 times the thickness of the finished steel plate. The thickness of the continuous casting billet limits the thickness of the finished steel plate, and it is difficult to reach more than 150mm

[0005] The Chinese patent of CN109722601A discloses a method for manufacturing extra-thick steel plates with a maximum thickness of 150mm EH420, which has strict requirements on the quality of continuous casting slabs, and it is necessary to control the center segregation of the slab C class ≤ 0.5, and the center porosity ≤ 0.5, which is difficult to meet Mass production, low pass rate, high cost

[0006] The Chinese patent of CN109022667A discloses a Q420E extra-thick steel plate with a maximum thickness of 210mm, which is rolled by die-cast steel ingots, does not get rid of the limitation of conventional compression ratio, and needs normalizing treatment, which is costly and has a long production process

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