# US 2013/0156637 A1 · Induction stirred, ultrasonically modified investment castings and apparatus for producing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0156637 A1 - Document ID: US20130156637A1 - Status: Published application - Kind: A1 - Application number: 13/330,879 - Filed: 2011-12-20 - Published: 2013-06-20 - Earliest claimed: 2011-12-20 - Assignees: General Electric Company - Inventors: Junyoung PARK; Jason Robert PAROLINI; Ibrahim UCOK - Web page: https://patentgrep.com/patent/US20130156637A1 ## CPC - B22C 9/043: {Removing the consumable pattern} - B22C 7/02: Lost patterns - B22D 27/02: Use of electric or magnetic effects {(for continuous casting B22D11/015, B22D11/11)} - B22D 27/04: Influencing the temperature of the metal, e.g. by heating or cooling the mould - B22D 27/045: {Directionally solidified castings} - B22D 27/08: Shaking, vibrating, or turning of moulds - B22D 27/20: Measures not previously mentioned for influencing the grain structure or texture; Selection of compositions therefor - B22C: FOUNDRY MOULDING (moulding refractory materials in general B28B) - B22D: CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES (shaping of plastics or substances in a plastic state B29C; metallurgical processing, selection of substances to be added to metal C21, C22) ## Abstract A method for making an equiaxed investment casting. The method utilizes an ultrasonic generator to send an ultrasonic pulse into molten metal in an investment casting mold. The investment casting mold is positioned within a working zone of furnace having low output induction coils for generating a convection current in molten metal. The ultrasonic pulse separates dendrites growing from the face of the mold inward into the molten metal. Instead, equiaxed grains can nucleate within the molten metal. In addition, the ultrasonic pulse and the low output induction coils circulate the molten metal as solute is rejected from solidifying equiaxed grains. The mixing reduces the effects of segregation in the solidifying alloy and assists in nucleating equiaxed grains. ## Claims ### Claim 1 A casting unit comprising: an investment casting mold having a mold cavity; a furnace having a first zone that receives the investment casting mold, means for generating a convection current in molten metal in the mold when the mold is provided with molten metal, a refractory divider surrounding and defining the first zone; insulation surrounding the first zone; and an ultrasonic source for delivering an ultrasonic pulse into the mold cavity when the cavity is provided with molten metal and positioned in contact with the bottom of the mold. ### Claim 2 (depends on 1) The casting unit of claim 1 wherein the means for generating a convection current comprises low output induction coils. ### Claim 3 (depends on 1) The casting unit of claim 1 further including a first heating element positioned within the first zone between the investment casting mold and the refractory divider. ### Claim 4 (depends on 1) The casting unit of claim 1 further including a furnace top overlying the furnace. ### Claim 5 (depends on 4) The casting unit of claim 4 wherein the furnace top includes a melting zone, the melting zone in fluid communication with the mold cavity. ### Claim 6 (depends on 5) The casting unit of claim 5 further including a second heating element surrounding the melting zone. ### Claim 7 (depends on 1) The casting unit of claim 1 further including means for maintaining an atmosphere within the first zone. ### Claim 8 (depends on 7) The casting unit of claim 7 wherein the means for maintaining an atmosphere within the first zone includes a vacuum system drawing a vacuum on the first zone. ### Claim 9 (depends on 7) The casting unit of claim 7 wherein the means for maintaining an atmosphere within the first zone includes a vacuum system drawing a vacuum on the furnace. ### Claim 10 (depends on 7) The casting unit of claim 7 wherein the means for maintaining an atmosphere within the first zone includes a nonreactive gas atmosphere for the first zone. ### Claim 11 (depends on 7) The casting unit of claim 7 wherein the means for maintaining an atmosphere within the first zone includes a nonreactive gas system for the furnace. ### Claim 12 (depends on 4) The casting unit of claim 4 further including a stopper for regulating the flow of molten metal between the melting zone and the mold cavity. ### Claim 13 A casting unit comprising: an investment casting mold having a mold cavity; a furnace having a working zone that receives the investment casting mold, low output induction coils surrounding the working zone, a refractory divider separating the working zone from the low output induction coils surrounding the working zone; a first heating element surrounding the investment casting mold and positioned between the investment casting mold and the refractory divider; insulation surrounding the working zone; a melting zone; a fluid communication channel between the melting zone and the investment casting mold; a second heating element surrounding the melting zone; a stopper to regulate a flow of molten metal from the melting zone, through the fluid communication channel and into the investment casting mold in the working zone; an ultrasonic source for delivering an ultrasonic pulse into the mold cavity when provided with molten metal and positioned in contact with the bottom of the mold; and means for maintaining an atmosphere in the working zone of the furnace. ### Claim 14 A method for fabricating an equiaxed casting, comprising the steps of: providing an investment casting mold having a mold cavity; providing a furnace having a working zone that receives the investment casting mold, means for generating a convention current; a refractory divider surrounding the working zone; insulation surrounding the working zone; a first heating element positioned inside the working zone and positioned between the refractory divider and the mold cavity; and an ultrasonic source for delivering an ultrasonic pulse into the mold cavity when provided with molten metal and positioned in contact with the bottom of the mold; placing the investment casting mold into the working zone; providing molten metal to the investment casting mold; as the molten metal begins to solidify in the mold cavity, applying an ultrasonic pulse to the investment casting mold, the pulse having sufficient amplitude to disrupt a formation of dendrites growing within the investment casting mold, the pulse further mixing the molten alloy; continuing to apply the ultrasonic pulse to the investment casting mold to disrupt the formation of dendrites, mix the molten alloy and promote the formation of equiaxed grains as the molten metal solidifies. ### Claim 15 A method for fabricating an equiaxed casting, comprising the steps of: providing an investment casting mold having a mold cavity; providing a furnace having a working zone that receives the investment casting mold, means for generating a convention current, the means for generating surrounding the working zone, a refractory divider separating the working zone from the means for generating a convection current; insulation surrounding the working zone; a first heating element positioned inside the working zone, the refractory divider positioned between the means for generating a convection current and the first heating element; a melting zone for receiving metal; a fluid communication channel between the melting zone and the investment casting mold; a second heating element surrounding the melting zone; a stopper to regulate a flow of molten metal from the melting zone through the communication channel into the investment casting mold; an ultrasonic source for delivering an ultrasonic pulse into the mold cavity when provided with molten metal and positioned in contact with the bottom of the mold; and means for maintaining an atmosphere within the working zone of the furnace; placing the investment casting mold into the working zone and positioned in fluid communication with the melting zone to receive molten metal; providing molten metal from the melting zone; optionally heating metal in the melting zone to a first predetermined temperature with the second heating element; providing molten metal to the investment casting mold while maintaining an atmosphere within the working zone of the furnace; as the molten metal begins to solidify in the mold cavity, applying an ultrasonic pulse to the investment casting mold, the pulse having sufficient amplitude to disrupt a formation of dendrites growing within the investment casting mold, the pulse further mixing the molten alloy; continuing to apply the ultrasonic pulse to the investment casting mold to disrupt the formation of dendrites, mix the molten alloy and promote the formation of equiaxed grains. ### Claim 16 (depends on 15) The method of claim 15 wherein the means for generating a convection current includes a low output induction coil. ### Claim 17 (depends on 15) The method of claim 15 wherein the means for generating a convention current further includes the ultrasonic source. ### Claim 18 (depends on 15) The method of claim 15 wherein the means for maintaining an atmosphere is selected the group consisting of a non-reactive atmosphere and a vacuum. ### Claim 19 (depends on 15) The method of claim 15 wherein the ultrasonic pulse is generated in a frequency range from 15 kHz-25 MHz. ### Claim 20 (depends on 15) The method of claim 15 wherein the metal is initially provided to the melting zone in an unmelted state and the metal is melted by the second heating element in the melting zone. ### Claim 21 (depends on 15) The method of claim 15 wherein the metal is provided to the melting zone from a separate source in a molten state. ### Claim 22 (depends on 15) An investment casting made by the process of claim 15.