Vanadium-chromium microalloying large-specification 500MPa ultra-fine grain corrosion-resisting anti-seismic steel bar and preparation method thereof

Abstract

The invention discloses a vanadium-chromium microalloying large-specification 500MPa ultra-fine grain corrosion-resisting anti-seismic steel bar and a preparation method thereof. The steel bar comprises, by weight percent, 0.21-0.25wt% of C, 0.45-0.55wt% of Si, 1.25-1.40wt% of Mn, 0.30-0.35wt% of Cr, 0.065-0.080wt% of V, not larger than 0.040wt% of S, not larger than 0.045wt% of P, not larger than0.0070wt% of O, 0.0165-0.0200wt% of N and the balance Fe and inevitable impurities. The preparation method of the steel bar comprises the procedures of molten steel smelting, deoxidization alloying,LF furnace refining, casting, steel blank heating and controlled rolling and controlled cooling. A certain amount of vanadium-containing pig iron is added into a tapping steel ladle to replace the expensive vanadium alloy, the V content of molten steel is increased, and the adding quantity of the vanadium alloy is reduced; in the deoxidization alloying process, a small quantity of silicon-nitrogenalloy is added, the nitrogen content in the molten steel is increased, and the proportion value of V / N in the steel is reduced, transferring of V from the solid solution state to a carbonitride precipitated phase in the rolling process is promoted, and the precipitation strength effect of the steel is obviously improved; and the preparation method is low in production cost and high in process applicability and controllability.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a vanadium-chromium microalloyed large-scale 500MPa ultrafine-grain corrosion-resistant and shock-resistant 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 on...

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Problems solved by technology

[0004] At present, the domestic production technology for 500MPa high-strength seismic steel bars after the implementation of the GB / T 1499.2-2018 standard mainly adopts the vanadium nitrogen microalloying process, and the V content in the steel is controlled to ≥0.085wt%. The Vickers hardness and microstructure of the 500MPa high-strength steel bar meet the GB / T 1499.2-2018 standard, and the ferrite grain size of the steel bar microstructure is controlled at 9.5-11.0. However, the vanadium alloy is expensive, resulting in high production costs, which is not conducive to Reduction of production cost of steel bar enterprises and improvement of product market competitiveness

At present, there are no related patents and paper research reports on the preparation method of chrome-vanadium microalloying large-scale 500MPa ultra-fine grain anti-corrosion and anti-seismic steel bars in China.

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