Square and round billet continuous casting meniscus electromagnetic stirring system and method with magnetic shielding and multi-mode

Abstract

The invention provides a magnetic shielding type multi-mode meniscus electromagnetic stirring system and method for continuous casting of square and round billets. The system comprises a meniscus electromagnetic stirrer and a variable-frequency power source control system. The variable-frequency power source control system is connected with a tap of a coil of the meniscus electromagnetic stirrer to provide a variable-frequency power source for the meniscus electromagnetic stirrer. A meniscus electromagnetic stirring mode or a crystallizer stirring mode is realized by changing of a phase sequence and a phase angle of current in the coil. The meniscus electromagnetic stirring mode comprises two submodes enabling molten steel to form a first circulation area and a second circulation area respectively. The crystallizer stirring mode is selected for stirring steels high in internal quality requirement, and the meniscus electromagnetic stirring mode is selected for stirring steels high in superficial and under-skin quality requirement. The stirrer is free of limits of mounting space and mounting position, surface quality problems of cast billets are effectively solved, and excellent metallurgical effects of any cross sections and steels can be achieved.

Description

technical field [0001] The invention belongs to an electromagnetic flow control technology for molten metal continuous casting (continuous casting), and relates to a meniscus electromagnetic stirring system and method for continuous casting of square and round billets with magnetic shielding and multiple modes. The present invention is also applicable to conventional crystallizer electromagnetic stirring. Background technique [0002] The practice of continuous casting shows that the flow shape of molten steel in the mold not only affects the floating and removal of inclusions and air bubbles on the surface and inside of the slab, but also affects the behavior of the steel-slag free surface (referred to as free surface) in the mold and the behavior of the primary billet. Shell growth conditions have an impact. Due to the complexity and difficulty of controlling the behavior of the free surface in the mold, the control of the flow of molten steel at the free surface is the f...

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Problems solved by technology

[0003] However, there are some deficiencies in the metallurgical effect of the existing electromagnetic stirring technology for molds: 1. There are requirements for installation space

Although the existing mold electromagnetic stirrer can achieve good metallurgical effects for most steel types and sections, for steels with high surface quality requirements, due to its lower installation position, the cleaning and maintenance of non-metallic inclusions are difficult. Limited control of incipient solidification shell

3. The metallurgical effect of large cross-section square and round billets is limited

4. It is easy to cause corner cracks in billets with large aspect ratio

Since the electromagnetic stirring of the mold adopts the design of a pair of rotating magnetic field poles, the flow in the billet mold is in the middle and rotates around the center, forming a circular flow field, so the four corners present a vortex-like secondary loop. Once the inclusions enter it, they cannot be removed, forming corner slag inclusions, which seriously cause corner cracks or breakouts

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