Method and apparatus for melt flow control in continuous casting mold

Abstract

A method and apparatus for continuous casting of metal. The flow of molten metal is altered to eliminate or reduce the transfer of entrained mold flux slag and non-metallic particles to the vicinity of solidifying metal near the mold walls, thereby resulting in significantly reduced sliver and related defects. Flow modifier members are placed such that their larger surface is more aligned with the larger dimension of the interior volume of the vessel in which the member is placed. In a particular form, the members may be shaped as rectangular plates and placed substantially parallel to the longer interior wall of the vessel.

Description

[0001] This application claims the benefit of U.S. Provisional Application No. 60 / 633,241 filed Dec. 3, 2004.BACKGROUND OF THE INVENTION [0002] The present invention relates generally to the field of continuous casting of steel, and more particularly to a device and method for flowing molten metal in continuous castings that produces fewer defects in the cast product. [0003] In continuous casting of steel (such as plain carbon steel), molten metal is poured from a ladle or tundish into a water-cooled copper mold vessel by using a submerged entry nozzle (SEN). In the continuous casting process, steel begins to solidify as it comes in contact with the walls of the copper mold, the slab descending down the height of the vessel. The thickness of slabs produced in such a mold typically is about 9 to 12 inches (˜230 to 300 mm), whereas in a thin slab caster the thickness is only about 2 to 4 inches (˜50 to 100 mm), while the width is much larger, typically 60 to 72 inches (1500 to 1830 mm...

AI Technical Summary

Benefits of technology

[0007] These needs are met by the present invention, wherein a continuous casting system and a method of operating the system that incorporates the features discussed below are disclosed. By the present invention, the flow of metal is altered in such a way so that it reduces the transfer of the entrained mold flux slag and non-metallic particles to the vicinity of solidifying metal near the mold walls, thereby significantly reducing sliver and other defects. Although described with respect to the field of steel casting, it will be appreciated that similar advantages of cleaner metal casting with reduced defects, along with other advantages, may apply to other applications of the present invention. Such advantages may become apparent to one of ordinary skill in the art in light of the present disclosure or through practice of the invention.

[0011] According to yet another aspect of the invention, a method for controlling the flow of molten metal in a continuous casting system is disclosed. The method includes configuring a vessel to comprise a plurality of walls to produce an interior volume of the vessel in which casting of the molten metal takes place. The walls have height, width and thickness dimensions, where the width dimension is of greater size than the thickness dimension. Additionally, the method includes introducing a mixture of molten metal and gas into the interior volume such that a molten metal upper surface is defined by the top of the quantity of molten metal within the vessel's interior volume. Another part of the method includes placing a flow modifier member such as those previously described in a location within the interior volume between where the mixture introduction occurs and the wall that defines the thickness dimension of the interior volume. The orientation of the flow modifier member is such that a major surface (i.e., a larger surface) is angularly aligned closer to the wall that defines the vessel's width dimension. In this way, the velocity of molten metal flowing adjacent the molten metal upper surface is reduced.

Problems solved by technology

One especially troublesome flow pattern for the continuous casting of steel under such asymmetric flow conditions involves the tendency of the gas and molten metal that exits the SEN to contact the wider walls of the mold, after which they ascend to the free surface of metal.

This high velocity can cause shearing of the mold flux and the non-metallic inclusions from the interface, which in turn could be carried downward to the solidifying metal slab when molten metal contacts the opposing wall.

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