A kind of small size 600mpa anti-seismic threaded steel bar and its manufacturing method

Abstract

The invention discloses small-size 600MPa-level aseimatic twisted steel, comprising the following components by weight percent: 0.23-0.28% of C, 0.60-0.80% of Si, 1.00-1.60% of Mn, 0.12-0.14% of V, 0.010-0.030% of N, 0.55-0.60% of Cr, the balance of Fe and inevitable impurities, and also comprising any one or combination of more than two of 0.001-0.040% of Nb, 0.001-0.020% of Ti, 0.001-0.010% of Al, and 0.001-0.050% of Cu. The manufacturing method comprises the short flow technologies of smelting by a converter or an electric furnace; continuously casting and rolling a billet, and cooling a cooling bed. The small-size twisted steel produced by the components and the method has high tensile strength, high yield strength, high percentage elongation after fracture, and over 1.25 of yield ratio, and can meet the requirements of the aseimatic steel.

Description

technical field [0001] The invention relates to an anti-seismic steel bar and a manufacturing method thereof, in particular to a small-sized anti-seismic threaded steel bar with a yield strength greater than 600MPa and a manufacturing method thereof, belonging to the field of iron and steel metallurgy and steel rolling. Background technique [0002] High-strength steel bars, especially 600MPa steel bars, have superior properties such as high strength, large safety reserves, good seismic performance, saving steel consumption, and convenient construction. They are more suitable for high-rise, long-span, and earthquake-resistant building structures. Efficient new building materials. At present, the research and development of 600MPa-grade hot-rolled steel bar HRB600 has been gradually carried out in China, and some achievements have been achieved. However, the research and development of 600MPa-grade seismic steel bars has a certain bottleneck. The seismic steel bars require a ...

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Problems solved by technology

At present, the research and development of 600MPa-grade hot-rolled steel bar HRB600 has been gradually carried out in China, and some achievements have been achieved. However, the research and development of 600MPa-grade seismic steel bars has a certain bottleneck. The seismic steel bars require a strength-to-yield ratio of ≥1.25 and a maximum total elongation of ≥9. %, the current strengthening method of hot-rolled high-strength steel bars is mainly realized by refining the grains through micro-alloying technology, but the grain refinement will easily lead to a decrease in the strength-to-yield ratio, which is unfavorable for seismic performance

[0003] Small-scale rebar has the characteristics of large compression ratio, fast rolling and cooling speed, and it is easier to obtain a microstructure with fine grains. certain degree of difficulty

[0004] At present, the research and development of domestic 600MPa grade steel bars mainly adopts micro-alloying process, and the strength is improved by adding micro-alloying elements such as vanadium and niobium, but there are still problems such as low strength-to-yield ratio and unsatisfactory anti-seismic performance, such as Hebei Iron and Steel Chengde Company's application The patent publication number is 102383033A, and the title is "a 600MPa vanadium-containing high-strength hot-rolled steel bar and its production method". The V content is controlled at 0.08-0.12wt%, and the structure is ferrite + pearlite, R m / R eL m / R eL m / R eL <1.25, Agt not listed; "Niobium-titanium-boron microalloy HRB600 high-strength anti-seismic reinforcement and its preparation" applied by Kunming Iron and Steel Co., Ltd. of Wuhan Iron and Steel Group, although it meets the anti-seismic requirements, but the microstructure is needle-like and grain boundary-like Ferrite, pearlite and granular, lath-like bainite structure, complex process control, requires low rolling temperature and ultra-fast cooling after rolling, high requirements for equipment, and low final rolling temperature is easy to cause The production of quenched and tempered martensite does not meet the requirements of the standard for the structure

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