Nitrogenous niobium vanadium microalloying 500MPa and 550MPa high-intensity aseismic reinforcing steel bar and melting method

Abstract

The invention provides a nitrogenous niobium vanadium microalloying 500MPa and 550MPa high-intensity aseismic reinforcing steel bar and a melting method. The high-intensity aseismic reinforcing steel bar comprises the following ingredients in percentage by mass: 0.20 to 0.25 wt percent of C, 0.35 to 0.55 wt percent of Si, 1.35 to 1.58 wt percent of Mn, 0.013 to 0.025 wt percent of V, 0.019 to 0.032 wt percent of Nb, 0.065 to 0.085 wt percent of N, at most 0.040 wt percent of S, at most 0.040 wt percent of P and the balance Fe and unavoidable impurities. The reinforcement effect of microalloy V and Nb is sufficiently exerted through increasing the N and decreasing the V and the Nb, the addition of the ferrocolumbium and vanadium nitrogen alloy is reduced, and the addition of noble alloy issaved. Compared with the traditional vanadium nitrogen alloy microalloying 500MPa high-intensity reinforcing steel bar , the nitrogenous niobium vanadium microalloying 500MPa and 550MPa high-intensity aseismic reinforcing steel bar provided by the invention has the advantages that the alloying cost of the process is reduced by 65 to 75 Yuan / t steel over the same periods, the economic benefit is obvious, the process production cost is low, the applicability and the controllability are high, the produced 500MPa and 550MPa high-intensity reinforcing steel bar is widely applicable to highrise andlarge-scale constructional engineering, and the aseismic performance and the welding performance of the reinforcing steel bar are good.

Description

technical field [0001] The invention relates to a smelting method, in particular to a smelting method of nitrogen-rich niobium vanadium microalloyed 500MPa and 550MPa high-strength anti-seismic steel bars, belonging to the technical field of steelmaking. Background technique [0002] High-strength seismic steel bars of 500MPa and above have the advantages of high strength, large safety reserves, good seismic performance, saving steel consumption, and convenient construction. They are suitable for high-rise, long-span and earthquake-resistant buildings. New and more efficient building materials. At present, the European Union, the United States, New Zealand, Australia and other countries generally use 500MPa and above steel bars as their main building steel bars. In order to meet the needs of the rapid development of the construction industry and accelerate the upgrading of steel used in construction, in recent years China and local relevant departments have issued a series ...

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Problems solved by technology

The steelmaking production of the above-mentioned steel bar raw materials is usually completed on the converter, and the N content in the molten steel is low (only 40-50ppm). Although the vanadium-nitrogen microalloying process is adopted, the V / N ratio in the alloy is not ideal. After alloying, the N content in molten steel is still low, and the supersaturation of V and N compounds is not enough, resulting in the V / N ratio in the steel being significantly higher than the ideal stoichiometric ratio. Part of the vanadium exists in solid solution, and V(CN) The precipitation of the second phase is relatively small, and the strengthening effect of V has not been fully exerted, which eventually leads to the waste of some V resources and the increase of production costs, which squeezes the profit margin of the enterprise, and is not conducive to the development of high-strength seismic steel bars of 500MPa and above. Production and promotion of applications

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