Square billet hyperbolic-type submersed nozzle and manufacturing method thereof

Abstract

The invention belongs to the technical field of square billet continuous casting production and discloses a square billet hyperbolic-type submersed nozzle and a manufacturing method thereof. The method comprises the steps including designing of a hyperbolic-type nozzle; counterboring; tool machining; machining of the hyperbolic-type nozzle; spraying and the like. According to the method, by designing the shape of an internal hyperbolic-type channel of the nozzle, by means of the characteristic that the upper curvilinear section areas are gradually decreased, the volume proportion of a cavity in the upper portion of the nozzle is controlled, and the tendency that gas suction of the nozzle causes secondary oxidation is reduced; and by means of the characteristic that the lower curvilinear section areas are gradually increased, steel flow flows downwards in a dispersed mode, the impact depth in a crystallizer of molten steel is decreased, and the flow behavior of the molten steel in the crystallizer can be improved easily. According to the square billet hyperbolic-type submersed nozzle and the manufacturing method thereof, the portion, in the hyperbolic top position, of the channel ismachined into a ring shape, backflow formed after multiple times of reducing of the steel flow is mainly used for disturbing a center flow, the flowing speed of the center flow is decreased, and thesteel flow is controlled to decelerate on the whole.

Description

technical field [0001] The invention relates to the technical field of billet continuous casting production, in particular to a billet hyperbolic submerged nozzle and a manufacturing method thereof. Background technique [0002] In the process of continuous steel casting, the flow characteristics of the fluid in the mold are not only related to the heat transfer of the mold and the floating of inclusions, but also have a very close relationship with the surface and internal quality of the slab. The submerged nozzle is the channel for molten steel to enter the mold from the tundish. It not only protects the steel flow and prevents secondary oxidation of the molten steel, but also changes the flow state of the molten steel in the mold. The submerged nozzle with a reasonable structure makes the The impact depth of molten steel decreases, which promotes the floating of inclusions in the crystallizer, and moves the high temperature zone upward, which is beneficial to the uniform ...

AI Technical Summary

Problems solved by technology

[0004] In the current continuous casting production process, the submerged nozzle used is a cylindrical inner cavity, which has the following defects in the use process: 1. The upper and lower channels of the cylindrical inner cavity are the same size, the velocity of molten steel increases under the action of potential energy, and the cross-sectional area of ​​the steel flow When the nozzle becomes smaller, the proportion of the diameter of the lower part of the nozzle decreases, forming a vacuum effect, causing secondary oxidation of the molten steel after the nozzle sucks air; 2. The speed of the steel flow increases after passing through the cylindrical inner cavity, and the molten steel has a large Kinetic energy increases the impact depth in the mold, resulting in large fluctuations in the liquid level of the mold, which is not conducive to the stable liquid level control in the pouring process. There will be problems such as mold mold slag being involved or liquid mold slag flowing in discontinuously, resulting in rolling 3. For steels with high quality requirements, the impact depth directly affects the use effect of electromagnetic stirring. After the impact depth increases, the position of electromagnetic stirring will shift, and the dendrites at the solidification front cannot be crushed, resulting in The electromagnetic stirring effect of the crystallizer becomes worse

[0005] At present, with the increasing requirements of product quality, the continuous casting process needs to optimize the relevant parameters of the nozzle, so that the relevant parameters tend to be conducive to the development of product quality improvement. Through scientific calculation and verification, the billet hyperbolic nozzle is manufactured. In order to play a good role in improving the quality of the billet billet, this technology is still blank

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