Method and device for improving internal quality of large-section round billet

Abstract

The invention discloses a method for improving the internal quality of a large-section round billet, which comprises the following steps of: establishing a casting billet temperature field calculation model, and determining the temperature distribution condition of the casting billet through the casting billet temperature field calculation model in combination with the actual production condition; calculating the kish thickness of the casting blank according to the temperature distribution condition of the casting blank; calculating the stirring position according to the kish thickness of the casting blank, wherein the liquid core thickness at the position of a stirrer accounts for 30-55% of the kish thickness of the casting blank; and starting corresponding electromagnetic stirring equipment according to the obtained stirring position. According to the method and device, the casting blank temperature field calculation model is established, the temperature distribution condition of the casting blank is determined, and the kish thickness of the casting blank is calculated according to the liquidus temperature and solidus temperature of the steel grade, so that the optimal stirring position can be determined when parameters such as the steel grade, the pulling speed or the secondary cooling water quantity change; the quality defects such as looseness, shrinkage cavities and segregation of the casting blank at the solidification tail end are avoided, and therefore the internal quality of the casting blank is improved.

Description

technical field [0001] The invention relates to the field of continuous casting, in particular to a method and a device for improving the internal quality of a round billet with a large cross-section. Background technique [0002] The central segregation, central shrinkage cavity and porosity inside the slab are the main internal defects of the continuous casting slab. Due to its small specific surface area and small radiation heat transfer in the secondary cooling zone, the large cross-section round billet has a slow heat dissipation, which makes the solidification distance longer and the bridging of the solidification process is more serious, which often leads to serious central segregation, looseness and shrinkage of the billet. Holes and other internal quality defects. On the other hand, large-section round billets are mostly high value-added steels, which have more stringent requirements for slab center segregation, porosity, and shrinkage cavities. [0003] In view o...

AI Technical Summary

Problems solved by technology

At present, the terminal electromagnetic stirring is installed at a fixed position of the casting machine, and the length of this position is only 0.6-0.8m. The disadvantages brought by the too short stirring area are: on the one hand, the production conditions of the continuous casting process are harsh. When factors such as steel type, casting speed or water quantity change slightly, the best stirring position may be staggered; ; Again, the action time is too short to give full play to the stirring effect of the end stirring

[0005] In response to the above problems, the application number is CN201910928262.7, which discloses a method for producing high-carbon manganese-chromium steel from large-section continuous casting round billets. In order to improve defects such as segregation, porosity, and shrinkage holes inside the billet, and to play the role of electromagnetic stirring at the end , first recommend a suitable stirring position at the end of the installation through calculation, and secondly, when the actual production changes due to changes in cross-section, superheat, etc., adjust the pulling speed to make the stirring position at the installation position of the final stirring equipment. The method has the following defects: 1. It is necessary to adjust the casting speed of the casting machine to play the function of final stirring, but the casting machine’s casting speed cannot be adjusted arbitrarily due to the production rhythm of the casting machine; The best stirring position may be staggered from the final stirring installation position

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