Casting method and cast article

Patent metadata

Field	Value
Publication number	US-9555471-B2
Application number	US-201414165719-A
Country	US
Kind code	B2
Filing date	Jan 28, 2014
Priority date	Jan 28, 2014
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

A casting method and cast article are provided. The casting method includes providing a casting furnace, the casting furnace including a withdrawal region in a lower end, positioning a mold within the casting furnace, positioning a molten material in the mold, partially withdrawing the mold a withdrawal distance through the withdrawal region in the casting furnace, the withdrawal distance providing a partially withdrawn portion, then reinserting at least a portion of the partially withdrawn portion into the casting furnace through the withdrawal region, and then completely withdrawing the mold from the casting furnace. The reinserting partially re-melts a solidified portion within the partially withdrawn portion to fill pores formed therein with the molten material. The cast article includes a microstructure and a porosity corresponding to being formed by a process comprising partially withdrawing, reinserting, and completely withdrawing of a mold from a casting furnace to form the cast article.

First claim

What is claimed is:

1. A casting method in a casting furnace, the casting furnace comprising a withdrawal region in a lower end, the method comprising:
positioning a mold within the casting furnace;
positioning a molten material in the mold;
partially withdrawing the mold a withdrawal distance through the withdrawal region in the casting furnace, the withdrawal distance providing a partially withdrawn portion, at least partially solidifying the partially withdrawn portion; then
reinserting at least a portion of the partially withdrawn portion into the casting furnace through the withdrawal region, at least partially re-melting the partially withdrawn portion; and then
completely withdrawing the mold from the casting furnace through the withdrawal region, producing a directionally solidified or single crystal cast article;
wherein the reinserting partially re-melts a solidified portion within the partially withdrawn portion to fill pores formed therein with the molten material.

2. The casting method of claim 1 , comprising varying a partial withdrawal rate during the partially withdrawing of the mold, the varying corresponding to portions of the mold including increased pore forming characteristics.

3. The casting method of claim 1 , comprising varying a complete withdrawal rate during the completely withdrawing of the mold, the varying corresponding to portions of the mold including increased pore forming characteristics.

4. The casting method of claim 1 , comprising decreasing at least one of a partial withdrawal rate and a complete withdrawal rate corresponding to a portion of the mold including increased thickness.

5. The casting method of claim 1 , wherein the partially withdrawing of the mold comprises a partial withdrawal rate of between about 1 inch per hour and about 10 inches per hour, the completely withdrawing of the mold comprises a complete withdrawal rate of between about 1 inch per hour and about 10 inches per hour, and the reinserting comprises a reinsertion rate of between about 1 inch per hour and about 20 inches per hour.

6. The casting method of claim 5 , wherein the partial withdrawal rate differs from the complete withdrawal rate.

7. The casting method of claim 5 , wherein the reinsertion rate is greater than the partial withdrawal rate and the complete withdrawal rate.

8. The casting method of claim 5 , wherein the reinsertion rate, the partial withdrawal rate, and the complete withdrawal rate are equivalent.

9. The casting method of claim 1 , further comprising a partial withdrawal hold time prior to the reinserting, and a reinsertion hold time prior to the completely withdrawing.

10. The casting method of claim 1 , further comprising positioning one or more additional molds within the casting furnace.

11. The casting method of claim 10 , wherein the positioning of the one or more additional molds is selected from the group consisting of vertical indexing, calculated guiding, thermally semi-insulating gaps formed between the one or more additional molds, and combinations thereof.

12. The casting method of claim 1 , wherein the withdrawal distance is between about 0.250 inches and about 6.0 inches.

13. The casting method of claim 1 , further comprising repeating the partially withdrawing and the reinserting of the mold prior to the completely withdrawing.

14. The casting method of claim 13 , wherein the repeating of the partially withdrawing exposes a previously-unexposed portion of the mold, and the repeating of the reinserting partially re-melts the solidified portion in the previously-unexposed portion of the mold.

15. The casting method of claim 1 , wherein the partially withdrawing and the reinserting of the mold reduces a porosity of the cast article.

16. The casting method of claim 1 , wherein the partially withdrawn portion comprises a turbine bucket tip shroud, and the cast article comprises a turbine bucket.

17. A casting method in a casting furnace, the casting furnace comprising a withdrawal region in a lower end, the method comprising:
positioning a mold within the casting furnace;
positioning a molten material in the mold;
partially withdrawing the mold through the withdrawal region in the casting furnace for a withdrawal time to provide a partially withdrawn portion, at least partially solidifying the partially withdrawn portion;
reinserting at least a portion of the partially withdrawn portion into the casting furnace through the withdrawal region, at least partially re-melting the partially withdrawn portion; and then
completely withdrawing the mold from the casting furnace through the withdrawal region, producing a directionally solidified or single crystal cast article;
wherein the reinserting partially re-melts a solidified portion in the withdrawn portion of the mold to fill pores formed therein with the molten material.

Assignees

• Gen Electric

Inventors

• Zheng Jian
• Peck Arthur S

Classifications

• B22D25/06 Primary

  by its physical properties (B22D27/00 takes precedence) · CPC title

• C30B11/003

  Heating or cooling of the melt or the crystallised material · CPC title

• C30B29/52

  Alloys · CPC title

• C30B11/006

  Controlling or regulating · CPC title

• B22D27/045

  Directionally solidified castings · CPC title