A 635mpa grade nb-v-cr composite reinforced high-performance steel bar and a smelting method thereof

Abstract

This invention discloses a 635MPa grade niobium-vanadium-chromium composite reinforced high-performance steel bar and its smelting method. By controlling the chemical composition and V / N mass ratio of the steel bar within the range of 3.35 to 3.75, and employing a multi-element composite strengthening formula of niobium, vanadium, and chromium to replace the traditional single vanadium-nitrogen alloy addition mode, production costs are reduced. During the smelting process, a dedicated dry powder stirring device is used to pre-mix the microalloying reinforcing agent, achieving uniform mixing of powder components and removal of magnetic impurities. Simultaneously, a composite desulfurizing agent is introduced and a step-by-step addition process is adopted, combined with a gradient ladle bottom-blowing argon stirring system, to effectively reduce the sulfur content in the steel. The steel bar prepared by this invention has a uniform microstructure, high grain size, and excellent mechanical properties such as tensile strength, yield strength, strength-to-yield ratio, and elongation. It exhibits good product consistency, low production costs, and can stably mass-produce high-performance 635MPa grade high-strength earthquake-resistant steel bars.

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