Crack-free fabrication of near net shape powder-based metallic parts
View Patent ↗Crack-free powder-based, near net shaped parts are fabricated using a die assembly and cold isostatic pressing. Soft materials are introduced on both sides of die components in order to balance compression loads applied to the die component, and thereby avoid deformation of the die component.
1. A method of fabricating a near net shape metallic part, comprising:
placing at least one die component inside a flexible container, the at least one die component having opposite sides and a plane of overall symmetry, wherein the at least one die component has a center of stiffness about the plane of overall symmetry;
filling the flexible container with a metallic powder, including placing the metallic powder on both sides of the plane of overall symmetry and contacting the opposite sides of the at least one die component;
compacting the metallic powder on a first side of the at least one die component into a powder compact, including compressing the flexible container, such that forces applied to the at least one die component are substantially balanced on each side of the plane of overall geometry;
removing the powder compact from the container; and
sintering the powder compact into a solid part.
2. The method of claim 1 , wherein the metallic powder is a hydride-dehydride blended-elemental powder titanium alloy composition.
3. The method of claim 1 , wherein compacting the metallic powder into a powder compact is performed using cold isostatic pressing.
4. A method of producing a crack-free metallic powder compact, comprising:
adding a metallic powder to a lower interior region of a flexible container;
placing at least one die component onto the metallic powder in the lower interior region of the flexible container to form a first metallic powder filled interior region;
adding the metallic powder to the flexible container on top of the at least one die component;
installing a container wall to form a second metallic powder filled interior region; and
compacting the metallic powder into a desired powder compact by subjecting the flexible container to a hydrostatic pressure.
5. The method of claim 4 , wherein compacting the metallic powder into the desired powder compact is performed by cold isostatic pressing.
6. A method of producing a crack-free metallic powder compact, comprising:
fabricating at least one stiff die component;
placing the at least one die component in a flexible container;
introducing a layer of metallic powder into the flexible container covering the at least one die component;
introducing a layer of soft powder material into the flexible container to balance loading of the at least one die component during compaction; and
compacting the metallic powder into a powder compact by subjecting the flexible container to a hydrostatic pressure, wherein compacting the metallic powder into a powder compact comprises compacting the metallic powder within a first interior region formed by the at least one die component and the flexible container, wherein a first side of the first interior region is formed by the at least one die component and a remainder of the first interior is fottned by the flexible container.
7. The method of claim 6 , wherein fabricating the die component includes producing a set of symmetric mirror image die features.
8. The method of claim 6 , wherein compacting the metallic powder is performed by cold isostatic pressing.
9. The method of claim 1 , wherein the flexible container is formed of one of a rubber or a plastic.
10. The method of claim 1 , wherein filling the flexible container with a metallic powder comprises creating two metallic powder filled interior regions that are mirror images of each other.
11. The method of claim 1 , wherein the at least one die component comprises a metal plate and a plurality of metal inserts movable within slots formed in the metal plate.
12. The method of claim 1 , wherein the plane of overall symmetry is between two interior regions within the flexible container.
13. The method of claim 4 , wherein the metallic powder is a hydride-dehydride blended-elemental powder titanium alloy composition.
14. The method of claim 4 , wherein the flexible container is formed of one of a rubber or a plastic.
15. The method of claim 4 , wherein the first metallic powder filled interior region and second metallic powder filled interior region are mirror images of each other.
16. The method of claim 4 , wherein the at least one die component comprises a metal plate and a plurality of metal inserts movable within slots formed in the metal plate.
17. The method of claim 4 , wherein compacting the metallic powder into a desired powder compact forms two crack-free metallic powder compacts having a same design.
18. The method of claim 6 , wherein the metallic powder is a hydride-dehydride blended-elemental powder titanium alloy composition.
19. The method of claim 6 , wherein the flexible container is formed of one of a rubber or a plastic.
20. The method of claim 6 , wherein the at least one die component comprises a metal plate and a plurality of metal inserts movable within slots formed in the metal plate.