Production of III threading reinforcing bar

Abstract

Production of 20MnSi III thread reinforcing bar is carried out by adding blast-furnace iron water and waste steel into oxygen rotary furnace or electric furnace, oxygen-blowing smelting or supply smelting, adding into manganese and reducing agent, slag-excluding and tapping while reaching to 20MnSi standard, adding into defoliant, ferro-silico-manganese alloy or manganese-ferro alloy or ferro-silicon alloy into steel bag sequentially, adding into nitrogen promoter to make nitrogen content 0.008-0.035%, adding into nitride-containing alloy, blowing argon or nitrogen for steel liquid at 0.01-0.10m3 / t.min for 2-9mins, rolling at 1050-1300degree, and penetration cooling at 1.5-1.5degree / second. It costs low and has excellent mechanical performance.

Description

Technical field [0001] The invention relates to a method for producing microalloy steel, in particular to a method for producing 20MnSi hot-rolled reinforced concrete with Class III threaded steel bars. Background technique [0002] Rebar is mainly used in the field of reinforced concrete engineering and construction, and it is required that the rebar have good performance, such as welding performance, cold forming performance and seismic performance. At present, there are four typical processes for producing 20MnSiIII-grade rebar: [0003] ①Microalloying process: that is, adding trace alloying elements such as vanadium (V), niobium (Nb), etc. to the molten steel to meet its mechanical performance requirements through microalloying of molten steel. This process technology is a mature process and is currently the most common technology for producing 20MnSiIII-grade threaded steel bars. The 20MnSiIII-grade threaded steel bars produced by this process technology have stable performa...

AI Technical Summary

Problems solved by technology

This process uses few alloying elements, hardly uses the expensive strategic elements vanadium and niobium, and the alloy cost is low; but this process technology requires precise control of the temperature of each process from the billet to the rolled product, which is difficult to control, so the mechanical properties of steel bars Large fluctuations in performance

In addition, its performance (such as welding performance, cold bending performance) is poor

[0005] ③Microalloying plus controlled rolling and controlled cooling process: This process is relatively mature, and the production cost of steel bars is lower than that of pure microalloying process, but this process does not overcome the shortcomings of controlled rolling and controlled cooling process, and it is necessary to add a set of controlled rolling and controlled cooling Equipment or system, equipment investment is large

This process is a new process for the production of grade III threaded steel bars. It adopts Q235 composition control, and the alloy cost is very low; but the problem is that low-temperature rolling is required, the current process needs to be modified or the capacity of the rolling mill must be increased, and the equipment investment is large. High roll consumption, high power consumption, high production costs, and welding problems