Acicular ferrite type high-strength steel bar and preparation method thereof

Abstract

The invention belongs to the technical field of hot-rolled ribbed steel bars for reinforced concrete structures, and particularly relates to an acicular ferrite type high-strength steel bar and a preparation method thereof. Steel in the steel bar comprises the following chemical components in percentage by weight: 0.25 to 0.35 percent of C, 0.40 to 0.80 percent of Si, 1.40 to 1.80 percent of Mn, less than or equal to 0.030 percent of P, less than or equal to 0.030 percent of S, 0.02 to 0.04 percent of Nb, 0.09 to 0.15 percent of V, 0.15 to 0.45 percent of Cr, 0.010 to 0.019 percent of N and the balance of Fe and inevitable impurity elements. Under the condition of existing process equipment of a production plant, the acicular ferrite type high-strength steel bar is prepared by adopting a high C, Si and Mn component design and a V and Nb combined microalloying mode and combining a rolling self-tempering process, the 700MPa-grade reinforcing steel bar with excellent comprehensive performance is produced on the premise of keeping material ductility, the yield strength of the 700MPa-grade reinforcing steel bar is greater than or equal to 700MPa, the tensile strength is greater than or equal to 830MPa, the percentage elongation after fracture is greater than or equal to 14%, the total elongation under the maximum force is greater than or equal to 9%, the anti-seismic performance is good, and the requirements of high-rise and large-span anti-seismic structures are met.

Description

technical field [0001] The invention belongs to the technical field of hot-rolled ribbed steel bars for concrete, and in particular relates to an acicular ferrite high-strength steel bar and a preparation method thereof. Background technique [0002] Compared with ordinary steel bars, high-strength steel bars have the advantages of high strength, excellent comprehensive performance, energy saving and environmental protection, long service life, and high safety performance. Foreign developed countries have already eliminated steel bars with lower strength levels such as 335MPa. Britain, Germany, Australia, France and other countries have widely used high-strength steel bars with a yield strength of 500MPa. rebar. In recent years, with the introduction of a series of high-strength steel promotion and application policies in my country, the percentage of high-strength steel consumption has increased year by year. At present, domestic HRB500 high-strength steel bars have been ...

AI Technical Summary

Problems solved by technology

There are the following deficiencies: tempering induction heater heating, grain stabilization treatment, etc., the process is complicated, which is not conducive to the promotion of large-scale industrial production

The disadvantages are: the N content is too high, it is easy to cause defects such as subcutaneous air bubbles in the continuous casting slab, and it will affect the plasticity index and aging performance of the steel bar

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