Ultra-fine grain high-strength and high-toughness 600MPa-grade anti-seismic steel bar and preparation method thereof

Abstract

The invention discloses an ultra-fine grain high-strength and high-toughness 600MPa-grade anti-seismic steel bar and a preparation method thereof. The steel bar comprises, by weight, 0.23 wt%-0.27 wt%of C, 0.45 wt%-0.57 wt% of Si, 1.42 wt%-1.55 wt% of Mn, 0.20 wt%-0.25 wt% of Cr, 0.012 wt%-0.017 wt% of Nb, 0.095 wt%-0.110 wt% of V, less than or equal to 0.040 wt% of S, less than or equal to 0.043wt% of P, less than or equal to 0.0070 wt% of O, 0.0240 wt%-0.0265 wt% of N and the balance Fe and inevitable impurities. The preparation method of the steel bar comprises the procedures of molten steel smelting, deoxidation alloying, molten steel argon station refining, molten steel casting, billet heating and billet controlled rolling and controlled cooling. According to the steel bar and the preparation method, a small amount of silicon-nitrogen alloy is added in the steel-making deoxidation alloying process, the nitrogen content in molten steel is increased, the V / N and Nb / N ratio value in steel is reduced, transfer of V and Nb from a solid solution state to a carbonitride precipitated phase in the rolling process is promoted, a large number of fine dispersed V (C, N) and Nb (C, N) precipitated phases are formed and precipitated, and the phase change temperature is reduced, so that the precipitation strengthening effect of the steel is obviously improved; and according to the method, the production cost is reduced, the anti-seismic property is improved, and the market competitiveness of the product is improved.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to an ultra-fine-grained high-strength and toughness 600MPa-grade anti-seismic steel bar and a preparation method thereof. Background technique [0002] Hot-rolled ribbed steel bar is the main reinforcement material of reinforced concrete building structure, and it carries the stress and strain of loads such as tensile and compressive stress and strain in the structure. At present, the annual output of hot-rolled ribbed steel bars in my country is about 200 million tons, which is the most widely used steel material in the construction of national economic construction projects. With the continuous development of my country's buildings towards high-rise, long-span and earthquake-resistant structures, the development of fine-grained anti-seismic steel bars with high strength, toughness and excellent comprehensive performance has become one of the important tasks for the...

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Problems solved by technology

[0004] After the implementation of the GB / T 1499.2-2018 standard, there are currently domestic research reports on the production technology of 600MPa straight anti-seismic steel bars after the implementation of the GB / T 1499.2-2018 standard. ≥0.130wt%, the 600MPa high-strength steel bars that meet the GB / T1499.2-2018 standard for macroscopic metallography, cross-section Vickers hardness, and microstructure are obtained through an appropriate controlled rolling process, and the grain size of the microstructure of the steel bar is mostly controlled at 9.5 to 11.0 , due to the high price of vanadium alloys, the production cost is high. In addition, the anti-seismic performance of steel bars produced by this process is not well matched, which is not conducive to the reduction of production costs of 600MPa high-strength steel bars and the improvement of product market competitiveness.

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