Non-contacting molten metal flow control

Abstract

Systems and methods are disclosed for using magnetic fields (e.g., changing magnetic fields) to control metal flow conditions during casting (e.g., casting of an ingot, billet, or slab). The magnetic fields can be introduced using rotating permanent magnets or electromagnets. The magnetic fields can be used to induce movement of the molten metal in a desired direction, such as in a rotating pattern around the surface of the molten sump. The magnetic fields can be used to induce metal flow conditions in the molten sump to increase homogeneity in the molten sump and resultant ingot.

What is claimed is: 
     
         1 . A system, comprising:
 a non-contacting magnetic source positionable adjacent an upper surface of molten metal for generating an alternating magnetic field suitable to control metal oxide migration along the upper surface, and   a controller coupled to the non-contacting magnetic source for controlling the alternating magnetic field.   
     
     
         2 . The system of  claim 1 , wherein the non-contacting magnetic source comprises one or more permanent magnets rotatably mounted about one or more axes, and wherein the controller is operable to control rotation of the one or more permanent magnets about the one or more axes. 
     
     
         3 . The system of  claim 1 , wherein the non-contacting magnetic source is positionable adjacent a meniscus of the upper surface to deform the meniscus. 
     
     
         4 . The system of  claim 1 , wherein the non-contacting magnetic source is positionable above the upper surface of the molten metal and between a wall of a mold and a molten metal dispenser. 
     
     
         5 . The system of  claim 4 , wherein the non-contacting magnetic source is height-adjustable to selectively space the non-contacting magnetic source at a desired distance from the upper surface of the molten metal. 
     
     
         6 . The system of  claim 4 , wherein the alternating magnetic field is oriented to control migration of the metal oxide along the upper surface in a direction normal to the wall of the mold. 
     
     
         7 . An aluminum product having a crystalline structure with a maximum standard deviation of grain size at or below 200, the aluminum product obtained by introducing molten metal into a mold cavity and inducing molten flow in the molten metal by generating a changing magnetic field proximate an upper surface of the molten metal. 
     
     
         8 . The aluminum product of  claim 7 , wherein the maximum standard deviation of grain size is at or below 80. 
     
     
         9 . The aluminum product of  claim 7 , wherein the maximum standard deviation of grain size is at or below 45. 
     
     
         10 . The aluminum product of  claim 7 , wherein the average grain size is at or below 700 μm. 
     
     
         11 . The aluminum product of  claim 7 , wherein the average grain size is at or below 400 μm. 
     
     
         12 . The aluminum product of  claim 7 , wherein inducing molten flow in the molten metal further includes inducing sympathetic flow in the molten metal. 
     
     
         13 . The aluminum product of  claim 7 , wherein the maximum standard deviation of dendrite arm spacing is at or below 10. 
     
     
         14 . The aluminum product of  claim 7 , wherein the maximum standard deviation of dendrite arm spacing is at or below 7.5.