Process for vacuum decarburization of steel
AssigneeSumitomo Metal Industries, Ltd.
InventorsTakashi Fukui, Takami Ikeda
Life of this patent
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Abstract
A process for the vacuum decarburization wherein oxygen gas is blown downward upon the molten steel surface under reduced pressure from a height apart from said steel surface characterized by applying a Laval nozzle having a divergence calculated from the theoretical Mach number which is, in turn, determined by a definite equation as a lance to provide a desired dynamic pressure on said molten steel surface and a desired depth of impression formed in the molten steel. In this process, a cooling medium for cooling the lance with a cooling medium sprayed with water.
Claims5
A process for the vacuum decarburization of steel under reduced pressure by mounting a ladle filled with molten steel in a closed decarburization vessel and agitating the molten steel by blowing gas through a tuyere in the ladle to prevent oxidation of alloy metals in the low carbon range, the improvement comprising the steps of:
- blowing lancing oxygen through an oxygen lance using a laval nozzle having a nozzle exit Mach number in the range of 2 - 4 wherein the laval nozzle has a divergent passage from its throat to its tip;
- maintaining the laval nozzle at a fixed height above the surface of the molten steel;
- and
- controlling the flow rate of oxygen in accordance with variations in the presence within the vessel to maintain the Mach number in the above specified range in accordance with the following formula:
- ##EQU3## wherein M.sub.2 is the Mach number at the nozzle exit;
- P.sub.0 is the pressure in the lance in Kg/m.sup.2, absolute,
- P.sub.2 is the pressure in the vessel (kg/m.sup.2, absolute),
- and K is the ratio of specific heats at constant pressure and volume.
Dependencies are inferred from the claim text.