A low yield ratio marine steel plate with good welding performance and its manufacturing method

Abstract

The invention belongs to the field of steel material preparation, and particularly relates to a low-yield-ratio marine steel plate with good welding performance and a manufacturing method thereof. Thelow-yield-ratio marine steel plate comprises the following components of, by weight, 0.05%-0.09% of C, 0.1%-0.4% of Si, 1.0%-1.5% of Mn, less than or equal to 0.02% of P, less than or equal to 0.02%of S, 0.005%-0.03% of Als, 0%-0.6% of Ni, 0%-0.3% of Cu, 0.008%-0.05% of Nb, 0.005%-0.03% of Ti, 0.002%-0.01% of N, 0.02%-0.08% of V, 0%-0.3% of Mo, and the balance Fe and inevitable impurities, wherein the yield ratio of the steel plate is less than or equal to 0.80, the carbon equivalent Ceq is less than or equal to 0.41, and Pcm is less than or equal to 0.21. According to the low-yield-ratio marine steel plate with the good welding performance and the manufacturing method thereof, a certain content of N element is added, and second phase dispersion precipitation of V, Ti element is matched,so that the high-heat input welding performance and the low-temperature impact toughness of the steel plate are improved; and chemical components and the processes of high finish rolling temperature,low water inlet high red returning temperature and low cooling speed are combined, so that the high service safety with the yield ratio being less than or equal to 0.8 can be obtained, and a corresponding production process is formed while the high-service safety steel plate which is easy to weld with high heat input is obtained.

Description

technical field [0001] The invention belongs to the field of iron and steel material preparation, and in particular relates to a low-yield ratio marine steel plate with good welding performance and a manufacturing method thereof. Background technique [0002] With the rapid development of ocean engineering, steel is the main structure of ocean engineering, and its research and development level and production capacity are also constantly improving. The operating environment of marine engineering equipment is generally relatively harsh, so steel for marine engineering should have high comprehensive properties, such as excellent plasticity, low temperature impact toughness and high heat input weldability. At present, steel for marine engineering can meet most of the needs of the marine engineering market, but some high-grade special steels are still unable to be produced stably. Ultra-high-strength steel plates that are resistant to low-temperature impact, high-efficiency, eas...

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Problems solved by technology

Publication No. CN106574316A discloses that the carbon equivalent of steel plates for large heat input welding is 0.38-0.43, and the rolling process only limits the cumulative reduction below 850°C. This composition process cannot well guarantee the welding performance and yield of large-thickness finished steel plates. Strong specific performance

Publication No. CN104603314A discloses steel plates with excellent toughness in welded heat-affected zones using oxide metallurgy theory to design components. Its disadvantages are that it is quite different from existing processes and has high requirements for the shape, size and distribution of oxides. Production more difficult

The publication number is CN106756543A. The TMCP low-cost high-energy-input welding steel plate disclosed by the patent uses oxide metallurgy to improve the welding performance of the steel plate. The steelmaking and continuous casting process is complicated and difficult to implement. The addition of Nb elements in the steel plate will affect thermomechanical rolling. The effect of grain refinement in the process

The steel for ocean engineering disclosed by the publication number CN106191659A does not fully combine N elements with Ti, V and other elements, and does not make full use of the low-temperature rolling stage to control the structure of the steel plate, and cannot achieve the effect of low yield ratio

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