Dynamic soft reduction technologies for bloom continuous casting of heavy rail

Abstract

The invention discloses a process of continuous casting dynamic with less reduction heavy rail steel cogged ingot, the process is applied in the continuous casting of high carbon steel cogged ingot, which can not only evidently alleviate center segregation, center porosity, center line shrinkage, center crack and so on defects and prevent the casting ingot center crack, middle crack and so on underbead crack, but also can improve component homogenization of rail rolled by the casting ingot, stabilize and improve mechanical property and functional performance of the rail and reach technical requirements of the high speed rail. The technical measure as follows: controlling continuous casting pulling rate and molten steel temperature of the heavy rail steel, the continuous casting pulling rate is 0.60-0.80m / min, the molten steel superheating temperature is 15-40 DEG C; adopting even and assuasive control mode in the secondary cooling zone, the continuous casting ratio water amount is 0.25-0.30L / kg, the casting ingot surface temperature on the area with less reduction is 900-1020 DEG C; the reduction is controlled on the area with less reduction, the casting ingot solidification rate on the area with less reduction fs=30%-100%, total reduction is 1.6-7.0 mm.

Description

technical field [0001] The invention relates to a continuous casting process, in particular to a dynamic soft reduction process for high-carbon steel blooms such as heavy rail steel, so as to eliminate central segregation, central porosity, central shrinkage cavity, and central cracks of the bloom. Background technique [0002] Heavy rail steel belongs to high-carbon steel. During the solidification process, the dendrites are developed, and it is easy to form a dendrite "bridge" in the core of the slab. In addition, the effect of selective crystallization during the solidification process enriches a large amount of solutes with low melting points between the dendrites. , at the end of solidification, the strong suction force generated by the solidification and contraction of the solid-liquid two-phase region at the end of the solidification of the slab causes the residual liquid enriched in impurities between the dendrites to flow to the center and fill it, resulting in centr...

AI Technical Summary

Problems solved by technology

[0007] The beneficial effects of the present invention are that the central segregation of the heavy rail steel slab can be significantly reduced, the central segregation of the slab is ≤1.0, the carbon segregation index of the slab center is 1.01-1.05, and the average is 1.02; Center shrinkage cavity, slab center porosity ≤ 1.0 level, slab center shrinkage cavity ≤ 0.5 level; can effectively prevent internal defects such as slab center crack, middle crack, corner crack, slab center crack, middle crack, corner crack ≤0.5 level, and the ratio of casting slabs without internal defects reaches more than 90%; the surface defect-free rate of heavy rail steel continuous casting slabs reaches 100%, and the hot delivery and hot charging process of heavy rail continuous casting slabs is implemented to reduce the fuel consumption of heating furnaces and Oxidation and burning loss during the heating process of the slab; it can eliminate the central defect of the slab and increase the metal yield; it can improve the uniformity of the rail composition, and the deviation between the composition of any point on the cross-section of the rail and the smelting composition: [C]≤±0.019%, [Si]≤±0.019%, [Mn]≤±0.019%, [P]≤±0.003%, [S]≤±0.002%, meeting the technical requirements of 350km / h high-speed rail