Production method of low-cost Q345q series bridge steel plate

Abstract

The invention discloses a production method of a low-cost Q345q series bridge steel plate. The steel plate comprises the following chemical components in percentage by mass: 0.10-0.13% of C; 1.4 to 1.5 percent of Mn; the steel plate comprises the following components in percentage by weight: 0.25 to 0.35 percent of Si, less than or equal to 0.004 percent of S, less than or equal to 0.015 percent of P, 0.020 to 0.040 percent of Als, 0.02 to 0.03 percent of Nb, 0.002 to 0.012 percent of Ti and less than or equal to 0.0005 percent of B. The thickness of the produced steel plate is 8 to 40mm; the adopted production method comprises the steps of molten iron pre-desulfurization treatment, 120 t converter treatment, LF refining and RH vacuum degassing, continuous casting, slab heating, controlled rolling, stack cooling, (flaw detection), finishing, sampling inspection, identification and warehousing. By adopting a low-temperature high-pressure technology and a TMCP controlled rolling and controlled cooling technology, the nucleation rate of ferrite is increased, so that ferrite grains are refined, and controlled cooling after controlled rolling can improve banded structures, refine pearlite pellets and reduce the interlayer spacing of pearlite, so that the effects of refined grain strengthening and precipitation strengthening are fully exerted, and the mechanical property index of a product is increased; and the alloy cost is greatly reduced while various properties of the bridge steel reach the national standard.

Description

technical field [0001] The invention relates to a production method of low-cost Q345q series bridge steel plates. Background technique [0002] Bridge slabs are widely used in railway bridges, highway bridges, large-scale river-crossing, sea-crossing bridges and urban light rail and other key projects. Bridges with a span greater than 300mm are all designed with steel structures, which are characterized by simple structure, light weight, high safety, capable of withstanding large static and dynamic loads, and long service time. Bridge steel is required to have high strength and toughness, welding performance, yield ratio, and resistance to lamellar tearing. In order to meet the above requirements, the traditional composition design of domestically produced Q345q series (Q345qC / D / E) steel plates mostly adopts the addition of micro-alloying elements such as Nb, V, Ti, Ni, etc. The process is complicated and the production cost is high, so the alloy cost of this type of steel ...

AI Technical Summary

Problems solved by technology

In order to meet the above requirements, the traditional composition design of domestically produced Q345q series (Q345qC / D / E) steel plates mostly adopts the addition of microalloying elements such as Nb, V, Ti, Ni, etc., and the process is complicated and the production cost is high, so the alloy cost of this type of steel is reduced , which is of great significance to improve the economic benefits of enterprises

[0003] Chinese patent application publication number CN101880824B discloses "Q345q series extra-thick steel plate and its production method". The composition mass percentage of the invention is: C: 0.08-0.16%, Si: 0.20-0.50%, Mn: 1.15-1.60%, P≤0.020 , S≤0.010%, Ca: 0.0010~0.0025%, Als: 0.010~0.050%, V+Nb+Ti+Ni≤0.012%, carbon equivalent Cev≤0.43, the invention adds V, Nb, Ti, Ni content To ensure the strength of the steel plate, it is only suitable for extra-thick steel plates with a thickness of 130mm, and the production cost is relatively high

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