A hot-rolled ribbed steel bar with a strength-to-yield ratio ≥ 1.25 and its production method

Abstract

A hot-rolled ribbed steel bar having a strength-to-yield ratio of 1.25 or more comprises 0.17-0.25wt% of C, 0.4-0.8wt% of Si, 1.2-1.5wt% of Mn, 0.045wt% or less of P, 0.045wt% or less of S, 0.05-0.08wt% of V, 0.006-0.018wt% of N, and the balance of Fe and impurity elements, and has a specification diameter of 12-40mm. A production method of the hot-rolled ribbed steel bar comprises the following steps: desulfurizing molten iron; carrying out top-bottom blowing of a converter; carrying out component fine-adjustment at an argon station, and blowing in nitrogen; refining an LF furnace, and blowing nitrogen into the LF furnace; continuously casting; carrying out stacking cooling; heating casted blanks; carrying out rough rolling and finish rolling; and naturally cooling to room temperature. Nitrogen is blown to realize greatly reduced cost, greatly reduced vanadium alloy consumption, increased V (C,N) amount and dispersity with the increase of the content of N in steel, substantial reinforcement effect and stable mechanical performances on the premise that mechanical performances comprising a hot-rolled yield strength of above 530MPa, a strength-to-yield ratio of 1.25-1.30, an A value of 18% or more and an Agt value of 10 or more are guaranteed.

Description

technical field [0001] The invention relates to a steel bar and a production method thereof, in particular to a ribbed steel bar and a production method thereof, and is especially suitable for a hot-rolled ribbed anti-seismic steel bar whose strength-to-yield ratio is improved through vanadium-nitrogen microalloy strengthening technology and a production method thereof . Background technique [0002] Due to the frequent occurrence of earthquakes and other disasters, especially after the 5.12 Wenchuan earthquake, the seismic performance indicators of steel used in the construction industry have received widespread attention, and high-strength, high-yield ratio seismic steel bars will gradually become the mainstream. [0003] The hot-rolled ribbed anti-seismic steel bars produced at present all increase the yield strength and elongation of the steel bars by adding vanadium-nitrogen alloys. The shortcomings are: the country vigorously promotes the policy of high-strength steel ...

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Problems solved by technology

[0003] The hot-rolled ribbed anti-seismic steel bars produced at present all increase the yield strength and elongation of the steel bars by adding vanadium-nitrogen alloys. The shortcomings are: the country vigorously promotes the policy of high-strength steel bars, resulting in HRB500 produced according to conventional processes. The price of vanadium alloy has soared sharply, and the production cost is too high, which completely crowds out the space of enterprises, which is not conducive to the improvement of competitiveness of enterprises; vanadium nitrogen alloy is a kind of composite alloy, its preparation is complicated, expensive, high production cost, and the production motivation of enterprises is insufficient , the output cannot be scaled; my country's domestic vanadium resource reserves are very limited, and large-scale mining is not conducive to environmental protection and the utilization of valuable resources

Its shortcomings: the process of preparing vanadium alloy of pure vanadium and nitrogen-enhancing agent of pure nitrogen is complex and expensive, which increases the production cost of steel bars, and the enterprise is insufficiently motivated to realize mass production

[0006] Its shortcomings: the use of nitrogen alloys to increase the nitrogen content in steel, and the high alloy content in steel increases production costs, squeezes the profit margins of steel mills, and is not conducive to improving the competitiveness of enterprises

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