Regulation of a stream of molten metal

Abstract

The invention describes an article and method for reducing precipitation on a surface adjacent to a stream of molten steel that is flowing from one metallurgical vessel to a second metallurgical vessel or mold. The refractory article comprises a working surface having a perturbation that disrupts the laminar flow in a boundary layer adjacent to the surface. The resultant non-laminar flow reduces precipitation on the surface and provides a convenient point for the injection of inert gas. The method includes disrupting the laminar flow in a boundary layer adjacent to the working surface.

I claim:  
     
         1 . A refractory article for use in controlling a stream of molten metal during continuous casting comprising a working surface adjacent to the stream, characterized by at least one perturbation in the working surface sufficient to create non-laminar flow in a boundary layer of the stream and without significantly affecting flow in a remainder of the stream.  
     
     
         2 . The refractory article of  claim 1 , characterized by the article comprising a stopper rod, nozzle, shroud, slide gate plate or combinations thereof.  
     
     
         3 . The refractory article of  claim 1 , characterized by the article comprising an inner surface defining a bore, the bore having an inlet and an outlet, and at least a portion of the bore comprising the working surface.  
     
     
         4 . The refractory article of  claim 3 , characterized by the perturbation being near the inlet.  
     
     
         5 . The refractory article of  claim 1 , characterized by the working surface comprising a nose of a stopper rod.  
     
     
         6 . The refractory article of any one of claims  1 - 5 , characterized by the perturbation comprising a discontinuity.  
     
     
         7 . The refractory article of any one of claims  1 - 5 , characterized by the discontinuity comprising a step.  
     
     
         8 . The refractory article of any one of claims  1 - 5 , characterized by the discontinuity comprising a groove.  
     
     
         9 . The refractory article of any one of claims  1 - 8 , characterized by the discontinuity being immediately upstream of a diverging section.  
     
     
         10 . The refractory article of any one of claim  1 - 9 , characterized by the article including a gas-injection apparatus.  
     
     
         11 . The refractory article of  claim 10 , characterized by the gas-injection apparatus comprising a porous refractory.  
     
     
         12 . The refractory article of claims  10  or  11 , characterized by the gas-injection apparatus being adapted to inject gas at the perturbation.