A processing method for 700mpa grade green heat-treated high-strength steel bars

Abstract

The invention discloses a 700MPa-grade green-heat-treatment high-strength steel bar and a processing method thereof. The high-strength steel bar comprises 0.18-0.3wt% of C, 0.6-0.9wt% of Si, 1.3-1.9wt% of Mn, 0.05-0.1wt% of Cr, 0.01-0.05wt% of Nb, 0.10-0.20wt% of V, 0.01-0.03% of Ni, 0.002-0.004wt% of B, below 0.023wt% of P, below 0.023wt% of S, and the balance Fe. The high-strength steel bar has the advantages of realization of the yield strength reaching 700MPa, obvious yield point elongation, no disappearance of the yield point elongation with the prolongation of time, strong delayed fracture resistance and high plasticity, and processing method of the high-strength steel bar has the advantages of simplicity, easy operation, less pollution, electric energy and steel resource saving, and low production cost.

Description

technical field [0001] The invention relates to a processing method for high-strength steel bars, in particular to a processing method for 700MPa-level green heat-treated high-strength steel bars. Background technique [0002] At present, due to the development of the real estate industry and machinery industry, the demand for steel has greatly increased, and the requirements for steel are also getting higher and higher. The yield strength of the existing hot-rolled steel bars is relatively low, and the yield strength of the hot-rolled steel bars must reach It is very difficult to achieve such a high strength of 630Mpa and above, and the strength is so high that it is difficult to guarantee the yield platform. In the "Twelfth Five-Year Plan" of the national iron and steel industry, it was proposed to "accelerate the elimination of 335 MPa grade rebar", " Strengthen the research on the seismic performance of high-strength steel bars and high-strength concrete structural membe...

AI Technical Summary

Problems solved by technology

[0002] At present, due to the development of the real estate industry and machinery industry, the demand for steel has greatly increased, and the requirements for steel are also getting higher and higher. The yield strength of the existing hot-rolled steel bars is relatively low, and the yield strength of the hot-rolled steel bars must reach It is very difficult to achieve such a high strength of 630Mpa and above, and the strength is so high that it is difficult to guarantee the yield platform. In the "Twelfth Five-Year Plan" of the national iron and steel industry, it was proposed to "accelerate the elimination of 335 MPa grade rebar", " Strengthen the research on the seismic performance of high-strength steel bars and high-strength concrete structural members, and carry out the research and development of 600 MPa and above rebar products." Now, the HRB600 rebar produced by many large steel factories is mainly added by adding "V" or "VN" alloys. To achieve the purpose of improving the strength, the addition amount reaches about 0.15%. As we all know, the cost of adding alloys will increase by 300-400 yuan. Due to the limitation of factors, the quality of the products produced is also unstable, and the phenomenon of low strength and unqualified strength-to-yield ratio often occurs, especially for products with specifications below 14mm.

The steel disclosed in the invention patent (application number: 201110086374.6) is produced through the process of composition ratio, heating, cooling, quenching and tempering. Power consumption cost, but its plasticity is low and the strength ratio is small, and it is prone to instantaneous fracture, resulting in overall fracture and other accidents. In addition, the existing heat-treated high-strength steel processing methods have serious environmental pollution, waste of electric energy and steel resources, and high production costs. High disadvantage