Production method of four-segment high-strength aseismic reinforcement

Abstract

The invention discloses a production method of four-segment high-strength aseismic reinforcement, and belongs to the technical field of steel for earthquake proof construction. Controlled rolling and controlled cooling processes are low-temperature initial rolling of a heating furnace, water cooling before pre-segmentation, four-line pre-segmentation, four-line segmentation, finally rolling, and two-stage control cooling after rolling. The production method has the advantages that minimization of micro-alloy elements of four-line segmentation of phi12mm and phi14mm under the condition that the edge organization of a basic circle is P+F is achieved; and the problems of low-temperature phase change organization, four-line line difference, poor mechanical property and the like caused by bending and water cooling in the four-line low temperature segmentation and water cooling processes are avoided.

Description

technical field [0001] The invention belongs to the technical field of anti-seismic construction steel. In particular, it relates to a production method of four-segmented high-strength anti-seismic steel bars. Background technique [0002] In recent years, under the vigorous promotion of the National Development and Reform Commission and the Ministry of Housing and Urban-Rural Development, building steel bars have been further strengthened. If the 400MPa and 500MPa grades are used to replace the 335MPa grades, the amount of steel bars can be reduced by at least 10% and 19% respectively, and the country can reduce about 7 million tons and 13.3 million tons. Especially since the Wenchuan earthquake in 2008, the Ministry of Housing and Urban-Rural Development has vigorously advocated the use of high-strength seismic steel bars. The seismic steel bars should also meet R m / R el ≥1.25, R el / R el o ≤1.30, A gt ≥9%. In 2009, GB1499.2 further added that "the base circle of ...

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Problems solved by technology

[0006] (2) There is a large amount of bainite or martensite in the round edge structure of high-strength building steel bars produced by the traditional strong water-cooling waste heat treatment process after rolling, which mainly increases the strength through single phase transformation strengthening, and reduces ductility and plasticity and weldability (part Can not meet the requirements of electroslag pressure welding), strain aging sensitivity and low temperature brittleness increase

The original intention of fine-grained steel bars in theory is non-microalloying, but in practice, limited by equipment conditions (requiring ultra-low temperature and high compression), the coupling effect of deformation and phase transformation cannot be fully exerted

And the research results show that when the ferrite grain size is refined to 7 μm, the R m / R el Only 1.26, further refining ferrite grains to improve strength, R m / R el will increase - decrease

Restricted by the existing domestic and foreign rolling mill equipment level and anti-seismic performance indicators, it is difficult to realize industrial production

[0008] (4) Although there are currently six-strand divisions in China, the small-sized high-strength seismic steel bars above the third-strand have not realized the reduction of microalloying elements based on the P+F condition of the base circle edge structure. This is because the small-scale multi-strand Segmentation controlled rolling and controlled cooling process faces difficulties such as cooling uniformity, low temperature slitting forward, upper cooling bed bending and precise control of metallographic structure

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