F+P+B type low-yield-ratio and high-strength medium steel plate and production method thereof

Abstract

The invention discloses an F+P+B type low-yield-ratio high-strength medium steel plate and a production method thereof, and belongs to the technical field of high-strength medium steel plates. The steel plate comprises the following chemical compositions by weight percentage: 0.05-0.12% of C, 0.2-0.4% of Si, 1.7-2.0% of Mn, less than or equal to 0.015% of P, less than or equal to 0.015% of S, 0.02-0.05% of Al, 0.04-0.09% of Nb, 0.01-0.02% of Ti, 0.03-0.07% of V, 0.1-0.2% of Cr, 0.001-0.002% of B, and the balance of Fe and unavoidable impurities. The steel plate adopts a smelting, controlled rolling and mild ultra-fast cooling technology system, and has the advantages that precious metal elements such as Ni, Mo or Cu are not adopted, so that the alloy cost is low; thermal treatment techniques such as quenching or tempering are not adopted, so that the production cost is low; the production period is short; high-toughness, low-yield-ratio and high-strength steel can be produced stably; and the steel plate is applicable to fields of engineering machinery, coal machine industry and the like.

Description

technical field [0001] The invention belongs to the technical field of high-strength medium-thick plate steel, and in particular relates to an F (ferrite)+P (pearlite)+B (bainite) type low yield ratio high-strength medium-thick steel plate and a production method thereof. Background technique [0002] With the development of large-scale and light-weight construction machinery, steel plates used in steel structures must have high strength, good elongation performance, cold bending performance, welding performance and impact resistance. However, when the structural strength level is increased, the risk of brittle fracture of the structure increases, and the requirements for ductility-plasticity and yield-strength ratio are also more stringent, especially the yield-strength ratio. Yield strength ratio is a parameter that characterizes the overall uniform plastic deformation ability of materials due to overload. A lower yield strength ratio means that the steel plate has a highe...

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Problems solved by technology

[0003] Prior to the present invention, patent number: 201010599469 A kind of 800Mpa low yield ratio structural steel plate and its production method, using TMCP process and tempering heat treatment, the thickness specification of the steel plate is 10-40mm, yield strength ≥ 550Mpa, tensile strength ≥ 800Mpa, yield strength ratio<0.70, the disadvantage is that the steel uses Nb, V, Ti microalloying elements and high noble metal elements Ni, Mo and Cu are added at the same time, the alloy cost is high; the process adopts post-rolling tempering treatment , the process cost is also high

The disadvantage is that the steel uses Nb and Ti microalloying elements while adding higher noble metal elements Ni, which leads to high alloy cost; offline heat treatment is used in the process, and the process cost is also high

[0005] Patent No.: 201210168133 A low-yield ratio high-strength steel plate and its manufacturing method. The billet is heated, rough-rolled, finish-rolled, and accelerated-cooled to below 550°C after rolling, then air-cooled to room temperature, and then normalized at 760-840°C Treatment, yield strength ≥ 450MPa, tensile strength ≥ 800MPa, mainly suitable for construction, bridges, pipelines, offshore platforms and other fields, the disadvantage is that a high content of precious metal element Mo is added, and normalizing treatment is required after rolling. Increase the alloy cost and process cost of the steel plate, and increase the production cycle

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