2results about How to "High flex ratio" patented technology

The present application relates to a HRB500E earthquake-resistant steel bar and a preparation method thereof, belonging to the technical field of earthquake-resistant steel bar production. The chemical composition of the steel bar comprises: C: 0.20 wt%-0.25 wt%, Si: 0.50 wt%-0.75 wt%, Mn: 1.20 wt%-1.40 wt%, P: ≤0.030 wt%, S: ≤0.030 wt%, V: 0.05 wt%-0.08 wt%, Fe; the metallographic structure of the steel bar is: ferrite and pearlite. The preparation method of HRB500E earthquake-resistant steel bars provided in the present application eliminates the heating step of the heating furnace, and is optimized from the aspects of composition control, continuous casting billet drawing speed control, direct rolling insulation roller conveying control, start rolling temperature, finishing rolling entrance temperature, wire drawing temperature, air cooling process, roller speed, etc. The produced HRB500E earthquake-resistant steel bars have excellent organizational properties, mechanical properties, and earthquake-resistant properties, with performance parameters Rp0.2≥520Mpa, tensile strength Rm≥700Mpa, elongation≥18%, Agt≥9%, strength-to-yield ratio≥1.25, and yield-to-yield ratio≤1.2.

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.