500MPa-grade hot-rolled coiled reinforced bar and production method thereof

Abstract

The invention discloses a 500MPa-grade hot-rolled coiled reinforced bar and a production method thereof. According to the 500MPa-grade hot-rolled coiled reinforced bar, the hot-rolled yield strength Rel of the prepared 500MPa-grade hot-rolled coiled reinforced bar is greater than or equal to 500MPa, Rm is greater than or equal to 630MPa, the elongation A is greater than or equal to 15%, Agt is greater than or equal to 9%, the yield strength ratio is greater than or equal to 1.25, the yield standard ratio is less than or equal to 1.30, a metallographic structure mainly comprises ferrite and pearlite and contains no tempered martensite, the content of bainite is less than or equal to 9%, and the content of ferrite and pearlite is greater than or equal to 91%. According to the production method for the 500MPa-grade hot-rolled coiled ribbed steel bar with the obvious tensile test yield point, the alloy can be selected in a targeted mode for microalloying according to the V, Nb and Ti alloyresource market and price conditions, the enterprise production cost is greatly lowered, in addition, the process is not complex, and the product performance is stable.

Description

technical field [0001] The invention relates to long iron and steel products and a production method thereof, belonging to the field of iron and steel metallurgy production and manufacturing, in particular to a 500MPa hot-rolled coil and a production method thereof. Background technique [0002] From November 1, 2018, the latest national standard GB / T1499.2-2018 for hot-rolled ribbed steel bars was officially implemented. The new national standard canceled the 335MPa-level strength rebar, retained the 400MPa and 500MPa-level strength, and added 600MPa-level strength. It can be predicted that grade 4 and grade 5 steel bars represented by 400MPa and 500MPa will be more widely used in actual construction projects. Hot-rolled ribbed steel bars for reinforced concrete, referred to as "rebar", are steel products with a large volume and wide range. In recent years, domestic production and sales have exceeded 200 million tons per year. Rebar is divided into straight strips and wir...

AI Technical Summary

Problems solved by technology

Therefore, although the steel bars with no obvious yield point or no yield point meet the standard requirements, they do not meet the requirements of most users, and there are many such quality complaints

In addition, if the steel bar has no obvious yield point, its safety warning function during service after construction will be greatly reduced

[0005] After searching, the Chinese patent application number is CN201811410229.7 (publication number is CN 109468534A), which discloses "500MPa-level V-containing microalloy high-strength yield ratio seismic steel wire rod and its production method". The chemical composition is: by weight Percentage meter, C: 0.20%~0.25%, Si: 0.35%~0.65%, Mn: 1.20%~1.60%, P≤0.035%, S≤0.035%, V: 0.070%~0.170%, N: 0.0100%~ 0.0120%, the N content is high, and the control range is narrow, which will have a certain adverse effect on the smelting and casting process control and product quality, and the specification of the 500MPa grade V-containing microalloy steel wire rod is 8mm ~ 12mm, not applicable Produced on 6mm small-sized coil snails

[0006] Chinese patent application number is CN2008100019404.X (publication number is CN 101255492A) patent document, discloses " the production method that prevents niobium microalloying hot-rolled ribbed steel bar from having obvious yield point ", according to the difference of ambient temperature, the heating temperature The temperature ranges are given respectively for the temperature of the upper cooling bed and the temperature of the upper cooling bed, but the heating temperature is as low as 1040-1120°C. The low heating temperature is not conducive to the solid solution of niobium element, which not only affects the full utilization of microalloying elements, but also affects the capacity requirements of the rolling mill equipment. higher

In addition, the strength of the patented steel bar only reaches 400MPa level, which cannot meet the requirements of 500MPa level

[0007] Chinese patent application No. CN201210340408.4 (publication No. CN 102796962A) discloses "Niobium-Titanium-Boron Microalloy HRB600 High-Strength Anti-seismic Reinforcement and Its Preparation". Ti and other alloys, the production cost is high, and the production motivation of the enterprise is insufficient, so it cannot be scaled up

[0009] Chinese patent application number CN200510094836 and patent CN201110373116 complete alloy strengthening through niobium-titanium composite alloying, but the nitrogen content is low, and the content of Nb, Ti, and N is not limited, so the precipitation strengthening effect cannot be fully exerted, which is not conducive to reducing the alloy content , improve alloy utilization

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