Method and apparatus for stirring and treating continuous and semi continuous metal casting

Abstract

A method and apparatus for stirring and treating continuous and semi-continuous casting of metallic rods (12). The apparatus comprising: a stand (30) for suspending at least one electric arc electrode (24) over the upper surface of a metallic casting (14) after or during pouring, at least one electrode (24) for forming a moving electric arc (38) over the upper surface of the mettalic casting being cast, a second electrode, being the liquid metal (14), for completion of an electric circuit including said electric arc (38) and the liquid metal (14); and control means (34), connected between said apparatus and a power supply (36) and arranged to supply power to the plasma arc electrodes (14, 24), for monitoring the parameters of the electric arc (38). The invention also provides a method for casting the metallic rods (12) by using the above described apparatus.

Description

FIELD AND BACKGROUND OF THE INVENTION [0001] The present invention relates to metal continuous and semi continuous castings. More particularly, the invention provides an improved method and apparatus for stirring and treating continuous and semi-continuous casting to produce a high-quality cast of any desired length and cross section composed of a ferrous or of a non-ferrous metal. [0002] Continuous and Semi-continuous casting are the most commonly used methods for casting and producing semi-finished products such as plats, tubs, shits, etc. While continuous casting is the main method for casting ferrous alloys i.e. low carbon steel, stainless steel, etc., semi-continuous casting is the preferred method for casting non-ferros alloys such as aluminium and copper alloys. Both methods based on continuously pouring metal from a reservoir mostly known as the tundish or the distributor, to a cooled open mold. The mold is open both for metal entrance (usually from the top) and for metal ex...

AI Technical Summary

Benefits of technology

"The present invention provides an improved method and apparatus for producing better quality rods, without the need to consume great quantities of electric power. The apparatus includes a stand for suspending at least one electric arc electrode over the upper surface of a metallic casting after or during pouring, at least one electrode for forming a moving electric arc over the upper surface of the metallic casting being cast, and a second electrode, being the liquid metal, for completion of an electric circuit including the electric arc. The method involves continuously pouring the liquid metal into a mold for casting rods, providing an electric arc electrode and positioning it slightly above the upper surface of the molten metal, providing a second electrode in electrical contact with a section of the mold being electrically conductive, and applying an electric current to the electrodes to form an arc between them. The apparatus and method improve the quality of the rods, reducing voids, inclusions, porosity, dendrite, and grain size, and improving homogeneity. The invention also allows for the production of continuous rods with aspect ratios exceeding 1.8."

Problems solved by technology

Impurities from the ladle or the casting powder can form inclusions and further reduce the mechanical properties of the products.

Gases, from the atmosphere or other sources are also present in the liquid metal, these being the main cause of casting porosity.

Obviously this process is of no help in improving the microstructure of the metal.

However electromagnetic stirring consumes much electric power, cannot be applied to very large castings and has limited influence on ingots having aspect ratios (width / breadth ratio) in excess of 1.8

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