Hot rolled ribbed steel bar with yield-to-tensile ratio of less than or equal to 0.8 and Rel of more than or equal to 600MPa, and production method

Abstract

The invention relates to a hot rolled ribbed steel bar with yield-to-tensile ratio of less than or equal to 0.8 and Rel of more than or equal to 600MPa, which comprises the following chemical compositions in percentage by weight: 0.18-0.22% of C, 0.4-0.8% of Si, 1.2-1.4% of Mn, less than or equal to 0.015% of P, less than or equal to 0.015% of S, 0.065-0.08% of V, 0.020-0.030% of Nb, and 0.009-0.015% of N. A production method comprises the following steps: conducting conventional smelting and casting blanks; stacking and cooling the cast blanks to room temperature; heating a steel billet; conducting rough rolling; conducting fine rolling; naturally air-cooling to room temperature for later use. For the hot rolled ribbed steel bar, the yield strength is more than or equal to 630MPa, the tensile strength is more than or equal to 800MPa, the elongation rate A is more than or equal to 25%, Agt/% is more than or equal to 12.5%, and the hot rolled ribbed steel bar has excellent antisespic performance, namely the yield-to-strength ratio is less than 0.8, the hot rolled ribbed steel bar has excellent welding performance, the breaking positions after the hot rolled ribbed steel bar is elongated always occur on a parent metal, the bending test is qualified, and the hot rolled ribbed steel bar has no changing accidents or quality problem due to macro defect of the cast blanks.

Description

technical field [0001] The invention relates to a steel bar for construction and a production method thereof, in particular to a Rel≥600MPa hot-rolled ribbed steel bar with a yield strength ratio≤0.8 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, that is, high-strength, low-yield-ratio seismic steel bars will gradually become the mainstream. [0003] In the existing production, the mechanical properties of anti-seismic steel bars are improved by adding too much alloy and nitrogen, but the addition of too much alloy will not only increase the manufacturing cost, but also cause the carbon equivalent to be too high to deteriorate the welding performance ; Excessive nitrogen increase will cause shrinkage cavities, air bubbles, porosity, cr...

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Problems solved by technology

The disadvantage is that the V content exceeds 0.15%, and it mainly uses the solid solution strengthening of vanadium to improve the strength, and does not make full use of the precipitation strengthening of vanadium to improve the strengt

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