Thickness s355g10+n steel plate for marine structure and its production method

Abstract

The invention discloses a steel plate with a thickness of S355G10+N for marine structures, which relates to the technical field of iron and steel smelting. The maximum thickness of the steel plate is 150mm, and the chemical composition and mass percentage are as follows: C: 0.08%-0.14%, Mn: 1.30%-1.65%, Si: 0.10%~0.50%, P≤0.015%, S≤0.005%, Nb: 0.015%~0.030%, V≤0.03%, Ti: 0.10%~0.020%, Alt: 0.020%~0.055%, Ni: 0.10 %~0.50%, CEV≤0.43%, Pcm≤0.21%, the balance is Fe and unavoidable impurities. The 150mm extra-thick steel plate has excellent low-temperature toughness, especially the ‑40°C impact at 1 / 2 of the thickness is greater than 100J, and the welding performance is good, which better meets the use and service requirements of offshore structures.

Description

technical field [0001] The invention relates to the technical field of iron and steel smelting, in particular to a steel plate with a thickness of S355G10+N for marine structures and a production method thereof. Background technique [0002] S355G10 steel belongs to the grade in BSEN10225 standard "Weldable Structural Steel for Offshore Structures", which specifies the chemical composition, mechanical properties, welding performance, etc. of offshore structural steels. At present, my country has not yet formulated special standards for steel used in marine engineering. Domestically, low-carbon equivalent and micro-alloying are mostly used, and reasonable heat treatment processes (such as normalizing) are selected after controlled rolling to develop S355G10+N and S355NL steel plates, which can meet the requirements of some offshore steel plates. Application of platforms and structural parts. [0003] In terms of steel development for marine engineering, S355G10+N produced by ...

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Problems solved by technology

[0003] In terms of steel development for marine engineering, S355G10+N produced by normalizing process and S355G10+M product produced by TMCP process, such as: Patent CN 104726769 discloses "S355G10+N steel plate for thick offshore platform and its production method", its steelmaking Casting in ingot molds, followed by rolling into billets, the cost of steelmaking is high; due to the solidification of steel ingots, the penetration force of extra-thick plate rolling is affected, the impact technology at -40°C at 1 / 2 of the thickness is difficult, and the quality of flaw detection cannot be guaranteed

Patent CN 109628853 discloses "a kind of S355G10 extra-thick steel plate for ocean engineering and its manufacturing method". It adopts low-carbon composition design, TMCP process, and is produced by tempering process. Limited by the compression ratio of continuous casting billet, the maximum thickness of its production is 120mm, which cannot fully meet the needs of extra-thick steel plates over 120mm for marine engineering

[0004] Limited by the compression ratio of the existing continuous casting slab, because the EN10225 standard requires that the rolling compression ratio is not less than 4 times, the thickness of S355G10+N steel plates for general marine structures, such as S355G10+N extra-thick steel plates with a thickness of more than 100mm, mostly use steel ingots as raw materials for rolling In order to ensure a large compression ratio, and adopt normalizing heat treatment process for production, due to the influence of steel ingot solidification and the limitation of rolling penetration force of extra-thick plate, the impact technology at -40°C at 1 / 2 of the thickness of this extra-thick plate is very difficult , and the flaw detection quality cannot be guaranteed

However, the TMCP process and TMCP+tempering process produce the maximum thickness of only 100mm and 120mm, which cannot fully meet the needs of extra-thick plates over 120mm for marine engineering.