Shear induced grain refinement of a cast ingot

Abstract

Molten metal can be introduced into a liquid sump during direct chill (DC) casting, such as DC casting of aluminum, through a feed tube having a nozzle with an opening. The opening of the nozzle can be shaped and/or sized to generate a jet of molten metal within the liquid sump. The jet of molten metal can exhibit Reynolds number at or above a threshold amount. Such a jet can achieve improved metallurgical properties over standard casting techniques, such as improved grain refinement. A sufficiently high Reynolds number can be achieved by supplying the molten metal at a sufficiently high velocity. When supplying molten metal at a constant volumetric flow rate (e.g., to avoid fluctuations in casting speed), the nozzle can be crafted to have a smaller-than-standard diameter opening, thus generating a higher-than-standard velocity jet.

What is claimed is: 
     
         1 . A casting system, comprising:
 a feed tube couplable to a source of molten metal; and   a nozzle located at a distal end of the feed tube, the nozzle submersible in a molten sump for delivering the molten metal to the molten sump, wherein the nozzle is designed to supply the molten metal at a Reynolds number of at least 14,000.   
     
     
         2 . The casting system of  claim 1 , wherein the nozzle is designed to supply the molten metal at a Reynolds number of at least 64,000. 
     
     
         3 . The casting system of  claim 1 , wherein the nozzle is designed to supply the molten metal at a Reynolds number of at least 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, 30000, 31000, 32000, 33000, 34000, 35000, 36000, 37000, 38000, 39000, 40000, 41000, 42000, 43000, 44000, 45000, 46000, 47000, 48000, 49000, 50000, 51000, 52000, 53000, 54000, 55000, 56000, 57000, 58000, 59000, 60000, 61000, 62000, or 63000. 
     
     
         4 . The casting system of  claim 1 , further comprising a mold for receiving the molten metal, wherein the mold comprises one or more mold walls and a bottom block lowerable to support a solidifying ingot. 
     
     
         5 . A casting system, comprising:
 at least one feed tube couplable to a source of molten metal; and   a set of nozzles comprising one or more nozzles, wherein each of the one or more nozzles is located at a distal end of the at least one feed tube and is submersible in a molten sump for delivering the molten metal to the molten sump, wherein each of the one or more nozzles has an opening sized to achieve a jet of molten metal within the molten sump at a Reynolds number, wherein a sum of the Reynolds numbers of each jet of molten metal is at least 14,000.   
     
     
         6 . The casting system of  claim 5 , wherein the openings of the one or more nozzles are sized such that the sum of the Reynolds numbers of each jet of molten metal is at least 64,000. 
     
     
         7 . The casting system of  claim 5 , wherein the openings of the one or more nozzles are sized such that the sum of the Reynolds numbers of each jet of molten metal is at least 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, 30000, 31000, 32000, 33000, 34000, 35000, 36000, 37000, 38000, 39000, 40000, 41000, 42000, 43000, 44000, 45000, 46000, 47000, 48000, 49000, 50000, 51000, 52000, 53000, 54000, 55000, 56000, 57000, 58000, 59000, 60000, 61000, 62000, or 63000. 
     
     
         8 . The casting system of  claim 5 , wherein the set of nozzles includes at least two nozzles. 
     
     
         9 . The casting system of  claim 5 , further comprising a mold for receiving the molten metal, wherein the mold comprises one or more mold walls and a bottom block lowerable to support a solidifying ingot. 
     
     
         10 . A method, comprising:
 delivering molten metal from a metal source to a metal sump through a feed tube, wherein the molten metal generates one or more jets of molten metal within the metal sump upon exiting the feed tube, wherein each of the one or more jets of molten metal has a Reynolds number, and wherein a sum of the Reynolds numbers of each of the one or more jets of molten metal is at least 14,000.   
     
     
         11 . The method of  claim 10 , wherein the sum of the Reynolds numbers of each of the one or more jets of molten metal is at least 64,000. 
     
     
         12 . The method of  claim 10 , wherein the sum of the Reynolds numbers of each of the one or more jets of molten metal is at least 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, 30000, 31000, 32000, 33000, 34000, 35000, 36000, 37000, 38000, 39000, 40000, 41000, 42000, 43000, 44000, 45000, 46000, 47000, 48000, 49000, 50000, 51000, 52000, 53000, 54000, 55000, 56000, 57000, 58000, 59000, 60000, 61000, 62000, or 63000. 
     
     
         13 . The method of  claim 10 , further comprising solidifying the molten metal into an ingot using a mold comprising one or more mold walls and a bottom block lowerable to support the solidifying ingot. 
     
     
         14 . A metal product cast according to the method of  claim 10 . 
     
     
         15 . The metal product of  claim 14 , wherein an average grain size of the metal product is at or below approximately 130 μm. 
     
     
         16 . The metal product of  claim 14 , wherein an average grain size of the metal product is at or below approximately 129 μm, 128 μm, 127 μm, 126 μm, 125 μm, 124 μm, 123 μm, 122 μm, 121 μm, 120 μm, 119 μm, 118 μm, 117 μm, 116 μm, 115 μm, 114 μm, 113 μm, 112 μm, 111 μm, 110 μm, 109 μm, 108 μm, 107 μm, 106 μm, 105 μm, 104 μm, 103 μm, 102 μm, 101 μm, or 100 μm. 
     
     
         17 . The metal product of  claim 14 , wherein a maximum grain size of the metal product is at or below approximately 250 μm. 
     
     
         18 . The metal product of  claim 14 , wherein a maximum grain size of the metal product is at or below approximately 245 μm, 240 μm, 235 μm, 230 μm, 225 μm, 220 μm, 215 μm, 210 μm, 205 μm, 200 μm, 195 μm, 190 μm, 185 μm, 180 μm, 175 μm, 170 μm, 165 μm, 160 μm, 155 μm, 150 μm, 145 μm, 140 μm, 135 μm, or 130 μm. 
     
     
         19 . The metal product of  claim 14 , wherein a grain size spread of the metal product is at or below approximately 130 μm. 
     
     
         20 . The metal product of  claim 14 , wherein a grain size spread of the metal product is at or below approximately 125 μm, 120 μm, 115 μm, 110 μm, 105 μm, 100 μm, 95 μm, 90 μm, 85 μm, 80 μm, 75 μm, 70 μm, 65 μm, 60 μm, or 55 μm.