Method for making castings by directed solidification from a selected point of melt toward casting periphery

• US 7,987,897 B2
• Filed: 02/26/2009
• Issued: 08/02/2011
• Est. Priority Date: 03/27/2008
• Status: Expired due to Fees

• Current Assignee: Oleg Vladimirovich Anisimov, Yury Valeryevich Shtankin
• Original Assignee: Oleg Vladimirovich Anisimov, Yury Valeryevich Shtankin
• Inventors: Anisimov, Oleg Vladimirovich, Shtankin, Yury Valeryevich
• Primary Examiner(s): Ward; Jessica L
• Assistant Examiner(s): Yoon; Kevin E
• Application Number:
  US12/380,357
• Publication Number:
  US 20090242166A1
• Time in Patent Office: 887 Days
• Field of Search: 164/71.1, 164/122, 164/501
• US Class Current: 164/501
• CPC Class Codes: B22D 27/045 Directionally solidified castings

Abstract

The invention is related to the foundry practice. According to this invention, the method for making castings by directed solidification from a selected point of the melt toward the periphery of the casting comprises forming a casting in a mold having thermodynamic characteristics that allow uniform volume cooling of the melt to be effected to a temperature at which natural solidification processes are completed. To improve the structural isotropy of the casting formed, the cooling is effected at a rate not exceeding 0.5° C./sec. The casting is formed in a nonuniform field of force. The nonuniform field of force is set up by ultrasonic waves focused on a selected point of the melt to form therein a localized elevated pressure zone and to direct the solidification front from the zone toward the periphery of the casting. The nonuniform field of force is sustained in the mold until the cooling casting reaches a temperature at which the natural melt solidification processes are completed as the melt cools. Before the melt is poured into the mold, it is overheated to a level that, together with the thermodynamic characteristics of the mold allowing the melt therein to be cooled at a rate not exceeding 0.5 K/sec, sustains the liquid phase of the melt for a time sufficient for directed melt solidification to be effected from the selected point of the melt toward the periphery of the casting before the commencement of natural melt solidification processes as the melt cools. Subsequently, as the temperature at which natural solidification processes are completed is reached, the nonuniform field of force is removed, and casting cooling may continue at any reasonable rate.

Claims

1. A method for making castings by directed solidification of a melt advancing from a selected point thereof toward the periphery, comprising using a stationary mold to form a casting by uniform volume cooling of the melt in a nonuniform field of force, wherein the nonuniform field of force is produced by ultrasonic waves focused on a selected zone totally within the melt volume and a localized elevated pressure zone is formed therein, a solidification center is set up in said localized elevated pressure zone, and a solidification front is directed from said localized elevated pressure zone toward the periphery of the casting.

2. A method as claimed in claim 1, wherein uniform volume cooling of the melt is effected at a rate not exceeding 0.5°

C./sec.

3. A method as claimed in claim 1, wherein the extent of overheating of the melt poured into the mold is selected so as to sustain a liquid phase of the melt for a time sufficient to complete directed melt solidification from a selected point toward the periphery of the casting until natural melt solidification processes commence as the melt cools.

4. A method as claimed in claim 1, wherein the nonuniform field of force is removed as the casting temperature reaches the point at which natural solidification processes are completed, and casting cooling is continued.