Continuous casting method and device for double-nozzle cast ultra-thick plate blank

Abstract

The invention relates to a continuous casting method and a continuous casting device for a double-nozzle cast ultra-thick plate blank. First and second submerged nozzles for casting are vertically inserted into an ultra-thick plate blank continuous casting crystallizer, the upper ends of the nozzles are respectively communicated with a tundish, two independent passages are formed between the tundish and the crystallizer, and molten steel in the tundish is injected into the crystallizer through the passages; and the flow of each nozzle is controlled by using a supporting stopper rod above each nozzle in the tundish so as to realize liquid level control of the crystallizer. By using the method and the device, protective casting from the tundish to the crystallizer can be realized; the submerged nozzles are changed on line on the premise that the casting is not opened and the crystallizer is not cut off, so that the casting time of the tundish is improved; and meanwhile, based on structural optimization of the submerged nozzles, the distribution uniformity of the flow field and the temperature field in the ultra-thick plate blank crystallizer can be effectively improved, and the quality of the ultra-thick plate blank is remarkably improved.

Description

technical field [0001] The invention relates to the technical field of continuous casting of extra-thick slabs (slabs with a thickness of more than 400 mm), in particular to a continuous casting method and device for casting extra-thick slabs with double nozzles. Background technique [0002] In the continuous pouring process of molten steel, the submerged nozzle not only protects the steel flow and prevents the secondary oxidation of molten steel, but also can change the flow state of the injection flow in the crystallizer, and disperse the heat brought by the injection flow to promote the billet Uniform growth of the shell. In the conventional continuous casting process of billets, slabs and round billets, a single nozzle is used for casting, and only one submerged nozzle is used to flow the molten steel from the tundish into the mold. [0003] In order to make the molten steel flow field and temperature field in the mold reasonable, and ensure that the cast slab exits th...

AI Technical Summary

Problems solved by technology

At the same time, under the condition of low casting speed, it is difficult for the stream flowing out of the submerged nozzle of the mold to hit the narrow surface of the mold, and cannot form an upward reflow zone, so that the liquid surface of the mold is inactive, and the molten steel flows upward to the molten pool. The heat transfer on the surface decreases, which is not conducive to the melting of the mold slag, and the lubrication and heat transfer control ability of the mold slag cannot be exerted, and the probability of longitudinal cracks on the surface of the slab is high

In addition, as the stream impacts downward, the chances of floating inclusions in the molten steel entering the mold from the tundish will decrease, and more high-temperature molten steel will be brought to the lower part of the mold, which will affect the growth rate of the solidified billet shell and cause breakout more likely

Therefore, the use of a single nozzle is not suitable for casting extra-thick slabs

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