Smelting method for producing HRB500E straight reinforcing steel bar of phi 12-25 mm through microalloying

Abstract

The invention discloses a smelting method for producing an HRB500E straight reinforcing steel bar of phi 12-25 mm through microalloying. Chemical components of the reinforcing steel bar comprise 0.19%-0.25% of C, 0.60%-0.80% of Si, 1.10%-1.4% of Mn, not larger than 0.04% of S, not larger than 0.04% of P, 0.01%-0.015% of N, 0.03%-0.05% of Ti, 0.05%-0.07% of V, 0.1%-0.3% of Cr, not larger than 1.55% of the sum of the mass percents of Cr and Mn and not larger than 0.54% of Ceq. The smelting method comprises the steps that a pre-deoxidation composite slag washing agent is added in converter tapping, wherein the slag washing agent comprises, by mass percent, 5%-10% of fluorite, 65%-75% of calcium carbide and 15%-25% of limestone; and the pre-deoxidation composite slag washing agent is added after converter tapping is completed, then a silicon manganese alloy, silicon iron and a high-carbon ferrochrome are added in sequence, all the alloys must start to be added when 1 / 3 of tapping is completed, all the alloys are added when 3 / 4 of tapping is completed, a high-nitrogen composite enhancer is added after converter alloy adding is completed, the adding quantity is 0.6-0.8 kg / t, the high-nitrogen composite enhancer comprises 12%-20% of N and 18%-25% of Ti, soft blowing is carried out after ferrotitanium and vanadium nitrogen alloys are added, and the soft blowing effect is that the exposed diameter of broken steel slag molten steel is 100-200 mm.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and relates to a smelting method for producing Φ12-25mm HRB500E straight bars by microalloying containing Ti, V, N, and Cr, which meets the requirements of the GB / T1499.2-2018 standard. Background technique [0002] HRB500E is a steel bar grade specified in GB / T1499.2-2018 "Reinforced Concrete Part 2: Hot-rolled Ribbed Steel Bars". High-strength steel bars used in high-rise buildings. In GB / T1499.2-2018, the upper limit of C, Si, Mn, P, S elements and the upper limit of Ceq (carbon equivalent) are specified, and V, Nb, Ti and other elements can be added as needed; the N content in steel is also specified It should be no more than 0.012%. If there is a sufficient amount of N-binding elements in the steel, the N content can be appropriately relaxed. There is no upper limit for the N content relaxation. The requirements for the structure of steel should mainly be ferrite plus pearlite structure...

AI Technical Summary

Problems solved by technology

Adding Cr and Mn at the same time can improve the strength, but it will also cause non-ferrite pearlite structure in the steel structure, which will easily cause brittle fracture of the steel bar when it is bent, and increase the quality risk

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