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(11) | EP 3 187 281 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | DYNAMIC BONDING OF POWDER METALLURGY MATERIALS |
| (57) A dynamic compaction process comprising providing (200) a container (20;118) having
a cylinder shape; filling said container (20;118) with a first powder material (16;110;114);
and dynamically compacting (210) said first powder material (16; 110; 114). Aerospace
component manufactured by dynamic compaction.
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BACKGROUND
[0001] The present disclosure is directed to the improved process of dynamic bonding to create hybrid powder metallurgy parts.
[0002] Advanced aerospace designs continue to challenge materials and materials technology. While powder metallurgy materials offer unique advantages for many aerospace components, they could be further optimized if dissimilar materials could be bonded into a single component.
[0003] For example, in gas turbine engines, disks which support turbine blades rotate at high speeds in an elevated temperature environment. The separate portions of the disks are exposed to different operating conditions and temperatures. Thus, different combinations of mechanical properties are required at different locations. The high temperature rim portion has fatigue crack growth resistance and creep resistance, while the highly stressed hub portion has high burst strength at relatively moderate temperatures and fatigue crack growth resistance. The hub portion also has high resistance to low cycle fatigue for long component life.
[0004] Because of these differing requirements for the mechanical properties of the separate disk portions, and the extreme temperature gradients along the radius of a turbine disk, a single alloy is not well suited to satisfy the requirements of both the hub and the rim area of a modern turbine disk.
[0005] A possible solution is to use a dual alloy disk with different alloys used in the different portions of the disk, depending upon the properties desired. The disk has a joint region in which the different alloys are joined together to form an integral article.
[0006] Numerous techniques for fabricating dual alloy disks have been considered, such as fusion welding, inertia welding, diffusion bonding, bi-casting, and hot isostatic pressing which may be employed to consolidate powder used for one portion of a disk, such as the hub, and also to join it to the other portion. Many of these processes have drawbacks, for example, the disadvantage of hot isostatic pressing is that any impurities present at the joint prior to hot isostatic pressing will remain, and may be exacerbated by the lengthy time at elevated temperature and pressure.
[0007] Present powder-metallurgical techniques require three to four steps to produce a finished product. For example, producing tungsten requires pressing and pre-sintering, followed by a consolidation sinter and/ or several hot-working steps. Dynamic bonding eliminates the need for large presses and expensive hot-pressing dies. In many instances, actual production time and costs may be reduced.
SUMMARY
[0008] In accordance with the present disclosure, there is provided a dynamic compaction process that comprises providing a cylinder shaped container; filling the container with a first powder material; sealing the container; and dynamically compacting the first powder material.
[0010] In an exemplary embodiment the process further comprises removing unwanted gases by use of a vacuum on the container subsequent to filling the container.
[0011] In an exemplary embodiment the process further comprises forming a component from the first powder material.
[0012] In an exemplary embodiment the component comprises a casing part having a flange portion, and wall portion formed from the first powder material.
[0013] In an exemplary embodiment the component comprises a casing part having a wall portion comprising a first alloy material and a flange portion comprising a second alloy material.
[0014] In an exemplary embodiment the process further comprises forming a component precursor from the first powder material; and cutting at least one casing part from the component precursor.
[0015] In an exemplary embodiment the process further comprises dynamically compacting the first powder material by use of a compaction mat.
[0016] In an exemplary embodiment the process further comprises aligning the compaction mat at an exterior surface of the container opposite a mandrel assembly.
[0017] In an exemplary embodiment the process further comprises forming a solid backstop against forces created during the dynamic compaction.
[0018] In an exemplary embodiment the solid backstop comprises the mandrel assembly, the mandrel assembly being reusable.
[0019] In accordance with the present disclosure, there is provided an aerospace component comprising a first alloy powder metallurgy material bonded together with dynamic compaction.
[0024] In an exemplary embodiment the wall portion comprises said first alloy material and said flange portion comprises a second alloy material.
[0025] Other details of the dynamic bonding process are set forth in the following detailed description and the accompanying drawing wherein like reference numerals depict like elements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026]
FIG. 1 is a partial cross-sectional schematic representation of a turbine engine component preform to be formed from a powdered material dynamically compacted;
FIG. 2 is a partial cross-sectional schematic representation of an exemplary embodiment of a turbine engine component preform formed from a powdered material dynamically compacted;
FIG. 3 is a process diagram of an exemplary dynamic compaction process.
DETAILED DESCRIPTION
[0027] Referring now to FIG. 1, there is illustrated a turbine engine component precursor 10, such as a casing. For simplicity, only a portion of the component precursor 10 is shown, although it is understood that the component precursor 10 is a full cylindrical shape. It is contemplated that other components can be formed with the process, such as shafts, rotors, airseals, blades, vanes and the like. The exemplary turbine engine component precursor 10, when fully manufactured, has a flange portion 12 and a wall portion 14, shown in dashed lines D.
[0028] The turbine engine component precursor 10 may be formed from a titanium-based alloy or nickel based alloy or a composite of alloys formed together to optimize the material properties of each constituent alloy. In an exemplary embodiment, the flange 12, and wall 14 portions can comprise a first material 16 composition of titanium alloy or nickel alloy powder such as, Ni-Co-Cr-Al superalloy. In alternative embodiments, the flange portion 12 can comprise another second material 18 such as a nickel powder alloy such as, Ni-Co-Cr-Ta superalloy. The first material 16 can comprise properties that are best suited for a particular region of the component precursor 10, such as, the wall 14 region of the component precursor 10. The second material 18 can comprise properties that are best suited for another region of the component precursor 10, such as, the flange 12. In an exemplary embodiment, the first material 16 can be a lower cost alloy and the second material 18 can be a more expensive alloy, and in exemplary embodiments capable of operating at higher mechanical loads and having superior mechanical properties such as being able to operate under higher stress levels for example creep and stress rupture.
[0029] In one alternative, the component precursor 10 can be formed by use of dynamic consolidation or compaction of alloy powder metallurgy material(s), such as a nickel alloy powder. The terms dynamic consolidation and dynamic compaction as well as dynamic bonding can be used interchangeably throughout the description.
[0030] The alloy powder is subjected to dynamic compaction. Dynamic compaction is characterized as momentary application of an extremely high pressure. This is contrasted with the compression characteristic of press-sintered and hot-press methods used in other processes, which are conducted at a much lower pressure and are carried out over an extended period of time.
[0031] Dynamic compaction is best achieved by shock waves produced by, for example, contact with a shaped explosive charge, or by impact with a high-velocity projectile. The shock waves moving through the powder create pressures that are several times the flow stress of the binding metallic phase, typically several GPa (usually about 2 to 7 GPa.). Consolidation occurs by deformation of the powder particles and extrusion into void spaces between the particles. The material at or near the surface of the particle undergoes temperature pulses that range from microseconds to milliseconds, but these are quickly quenched by heat flow into the bulk of the powder particle. Since the heating is extremely short, it cannot support chemical reaction, melting, or other phase formation processes. Thus, it is possible to essentially preserve the original microstructure of the alloy material interface, with little or no chemical reaction or alloying. Thus, the formation of undesirable phases that can compromise the physical properties of the final compacted shape is avoided.
[0032] The component precursor 10 can be formed into a cylinder having a generally pentagonal shaped cross section, formed around a centerline CL. The shape as shown in figures 1 and 2, exemplifies a casing. It is contemplated that the precursor 10 can be formed into any variety of shapes, some of which are near net shaped geometry.
[0033] The component precursor 10 can be formed by filling a cylindrical shaped or more appropriately shaped container 20 with the first material 16 powder. Excess air/gases can be evacuated from the container 20. The container 20 is sealed by mechanical means and/or by welding. The sealed container is then subjected to instantaneous dynamic compaction (i.e., explosion) which applies very high pressure to exterior surfaces 22 of the container 20. The container is collapsed upon the internal powder 16, 18 with the high pressure force to form a solid powder metallurgy preform 24 encased by the container. The container is then removed by conventional machining.
[0034] A reusable mandrel assembly 28 is insertable inside the container 20 at an interior 30 of the container. The mandrel assembly 28 is designed to form a solid backstop against the forces created during the dynamic compaction. The mandrel assembly 28 can include a pair of tapered mandrel portions 32 coupled together by a tie rod 34. A pair of self-aligning end caps 36 can be included in the assembly employed to align and fix the tapered mandrel portions 32 into proper alignment. The mandrel assembly 28 includes a locating spacer 38 located on the tie rod 34 and between the pair of tapered mandrel portions 32 along a split line 40. The mandrel assembly 28 can be fastened together by nuts 42 fastened to the threaded ends of the tie rod 34. The mandrel assembly 28 can be reusable. The tapered mandrel portions 32 can comprise a high thermal expansion stainless steel material or conventional steel material.
[0035] A filling tube 44 is shown and can be substituted by a rigid cover (not shown), or an integral boss welded to the container 20 and an internally fitting plug (not shown) substituted for the filling tube 44. The container can be evacuated of air and other gases. In an exemplary embodiment, a vacuum of 10-6 Torr (133 µPa) can be applied to the container to prevent oxidation of the first powder material 16. The container 20 can be removed from the preform 24 to form the component precursor 10. A component 46 can be created from the component precursor 10.
[0036] The newly formed component 46 is now ready for subsequent processing, such as, forging and thermal mechanical processes as required to form the final shape of the component 46.
[0037] FIG. 2 shows an exemplary embodiment of a turbine engine component precursor 100 formed by a powdered material 110 dynamically compacted to a preform 112. The exemplary embodiment of FIG. 2 shares many similarities to the exemplary embodiment of FIG. 1. The preform 112 is similar to the preform 24 at FIG. 1, since it can be formed into a solid of virtually any shape formed by use of dynamic consolidation or compaction of alloy powder metallurgy material(s),(i.e., a first alloy 114 and/or second alloy 116), such as a nickel alloy powder. The second alloy 116 can be different from the first alloy 114. In an exemplary embodiment the entire component precursor 100 can be formed of a single powdered material 110.
[0038] The preform 112 in this embodiment, is a cylinder shape, having a predefined length L. In an exemplary embodiment the predefined length L can be several feet. The diameter (not shown) can be on the order of inches to feet and in an exemplary embodiment on the order of 20 inches to 50 inches (0.508 meters to 1.27 meters). The thickness of the preform 112 can be on the order of inches (cm) depending on the ultimate size of the turbine engine component precursor 100.
[0039] The powdered material 110 can be placed into a container 118 of appropriate size and shape. The container 118 can be sized, such that, the first alloy material 114, or alloy powder metallurgy material(s), can fill the container 118. In an alternative embodiment, the first alloy 114 can occupy a portion of the container 118, the second alloy 116 can occupy another portion of the container 118 as shown by demarcation lines 120. The container 118 can be a cylinder shape forming a cavity 122 that is configured to be filled with the alloy material 110. The cavity 122 includes a first portion 124 and a second portion 126 opposite the first portion 124. A central portion 128 is located between the first and second portions 124, 126 within the cavity as divided by the demarcation lines 120.
[0040] In the exemplary embodiment, the preform 112 can comprise the two different alloys 114, 116 in different locations in order to optimize the material properties of the two different alloys 114, 116 at particular locations in the preform 112, as described above. The powdered materials can be located in portions 124, 126, 128 of the cavity 122 to provide the material properties needed. Combinations of different alloys, and locations can be utilized in the design of the component precursor 100.
[0041] In the embodiment shown, the first alloy 114 can be located in the first portion 124, the second alloy can be located in the central portion 128, and the first alloy 114 can be located in the second portion 126. By this arrangement, the material properties of the second alloy 116 can be utilized at the central portion 128.
[0042] The component precursor 100 can be utilized to form casing parts 130 (shown in dashed lines D). The casing parts 130 can include a flange portion 132 and wall portion 134. By use of the current design and method, the casing parts 130 can comprise the flange portion 132 formed from the second alloy 116 and wall portion 134 formed from the first alloy 114. In this exemplary embodiment, the flange portion 132 can include material properties best suited for the flange area of a casing. The wall portion 134 can include material properties best suited for the walls of a casing.
[0043] A compaction mat 136 can be placed on the container 118 adjacent to an exterior surface 138 of the container 118. The compaction mat 136 covers the exterior surface 138 around the circumference of the container 118. The compaction mat 136 as shown, is placed on the exterior surface 138 opposite a mandrel assembly 140. The compaction mat 136 is configured to contain the explosive components that initiate the dynamic compaction. In an exemplary embodiment, the compaction mat 136 can include a composition of fertilizer (ammonium nitrate) and kerosene in the appropriate proportions to facilitate momentary application of an extremely high pressure. Other forms of explosive materials are also contemplated.
[0044] The alloy powder materials 114, 116 are dynamically compacted to form the preform 112. The container 118 can be removed from the preform 112 to have a newly formed component precursor 100.
[0045] The component precursor 100 can be formed as near net shape or cut into casing parts 130 as shown by the dashed lines D. The newly formed component precursor 100 is now ready for subsequent processing, such as, forging and thermal mechanical processes as required to form the final shape of a component 142, such as shown in dashed lines at Figs 1, 2.
[0046] In an exemplary embodiment, the component precursor 100 can be utilized for high volume production of components 142, such as casings, blades, vanes, airseals and other aerospace components.
[0047] FIG. 3 shows an exemplary process embodiment, namely the formation of a powdered material dynamically compacted preform. This exemplary embodiment is similar to the other exemplary embodiments shown in FIG. 1 and FIG. 2.
[0048] The first step includes providing a container 200. The component precursor or preform can be formed by dynamic compaction 210 of a first alloy material for the preform. The preform is then processed into a final shape 212.
[0049] Dynamic compaction provides an alternative method for compaction of powder metallurgy material as compared to conventional methods of compaction, such as, hot isostatic pressing or extrusion. The new method allows for the compaction of materials that previously may not have been capable of compaction via previously known methods. Dynamic compaction is achieved without the use of costly hot isostatic pressing or extrusion equipment and their associated facilities. Thus, the turn-around time for dynamic compaction process powder metallurgy material can be months faster that previously known method's wait times for extruded or hot isostatic pressed powder materials. The dynamic bonding techniques disclosed herein allow bonding of similar or dissimilar powder metallurgy material at ambient temperatures with low cost tooling and fixtures. A broader design space can be achieved by use of the disclosed process including hybrid powder metallurgy material combinations and configurations. The disclosed method enables the bonding of dissimilar materials and blend ratios, e.g., ceramic/metallic powders, insitu ceramic/metallic powders, nano insitu ceramic/metallic powders that could not previously be achieved.
[0050] The exemplary design allows for placement of certain alloy materials in areas of safety to allow for greater margins of safety in a casing design.
[0051] There has been provided a dynamic compaction process. While the dynamic compaction process has been described in the context of specific embodiments thereof, other unforeseen alternatives, modifications, and variations may become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations which fall within the broad scope of the appended claims.
1. A dynamic compaction process comprising:
providing (200) a cylinder shaped container (20;118);
filling said container (20;118) with a first powder material (16;110;114);
sealing said container (20;118); and
dynamically compacting (210) said first powder material (16; 110; 114).
2. The process according to claim 1, wherein said first material (16;110;114) comprises
a nickel alloy.
3. The process according to claim 1 or 2, further comprising:
removing unwanted gases by use of a vacuum on said container (20;118) subsequent to filling said container (20; 118).
4. The process according to any preceding claim, further comprising:
forming a component (46;142) from said first powder material (16; 114).
5. The process according to claim 4, wherein said component (46;142) comprises a casing
part (130) having a flange portion (12;132), and wall portion (14;134) formed from
said first powder material (16;110;114).
6. The process according to claim 4, wherein said component (46;142) comprises a casing
part (130) having a wall portion (14;134) comprising a first alloy material (16;114)
and a flange portion (12;132) comprising a second alloy material (18; 116).
7. The process according to any of claims 1 to 4, further comprising:
forming a component precursor (10;100) from the first powder material (16;110;114); and
cutting at least one casing part (130) from said component precursor (10;100).
8. The process according to any preceding claim, further comprising:
dynamically compacting said first powder material (16;110;114) by use of a compaction mat (136).
9. The process according to claim 8, further comprising:
aligning said compaction mat (136) at an exterior surface (22;138) of said container (20;118) opposite a mandrel assembly (28;140).
10. The process according to any preceding claim, further comprising:
forming a solid backstop against forces created during the dynamic compaction.
11. The process according to claim 10, wherein said solid backstop comprises said mandrel
assembly (28;140), said mandrel assembly (28;140) being reusable.
12. An aerospace component (46;142) comprising a first alloy powder metallurgy material
(16;110;114) bonded together with dynamic compaction.
13. The aerospace component according to claim 12, wherein said aerospace component (46;142)
is near net shape.
14. The aerospace component according to claim 12 or 13, wherein said aerospace component
(46;42) is a casing.
15. The aerospace component according to claim 14 wherein said casing comprises a wall
portion (14;134) and a flange portion (12;132), optionally, wherein said wall portion
(14;134) comprises said first alloy material (16;114) and said flange portion (12;132)
comprises a second alloy material (18;116).