METHOD FOR PRODUCING A BLADE FOR A TURBOMACHINE

Abstract

Disclosed is a method for producing a blade for a turbomachine, which method comprises: providing a blade root, having a first platform region, from a first material; providing on the first platform region at least one capsule that is filled with a metallic and/or ceramic powder that comprises at least one second material which is different from the first material, for producing a blade airfoil having a second platform region; producing and shaping a blade airfoil from the capsule that is filled with the powder by at least one thermal input method, thereby connecting the blade root to the blade airfoil in respective platform regions.

Also disclosed is a blade which is obtainable and/or obtained by this method.

Claims

1. A method for producing a blade for a turbomachine, wherein the method comprises: providing a blade root, having a first platform region, produced from a first material; providing on the first platform region at least one capsule that is filled with a metallic and/or ceramic powder that comprises at least one second material which is different from the first material, for producing a blade airfoil having a second platform region; producing and shaping a blade airfoil from the capsule that is filled with the powder by at least one thermal input method, thereby connecting the blade root to the blade airfoil in respective platform regions.

2. The method of claim 1, wherein the capsule is produced from the powder by a generative production method and is filled with the powder.

3. The method of claim 2, wherein the capsule is produced by electron beam melting and/or by selective laser melting,

4. The method of claim 2, wherein by the generative production method the capsule is produced by a layer-by-layer construction of the capsule on the blade root.

5. The method of claim 2, wherein prior to production of the capsule by the generative production method and/or prior to filling of the capsule the powder is heated to a heating temperature which is lower than a melting temperature and/or than a sintering temperature of the powder.

6. The method of claim 2, wherein the capsule is filled with the powder in that in the generative production method at least one part-region of the capsule is produced layer-by-layer from the powder as a hollow section that is closed on a circumferential side, and thereby at least a part-quantity of the powder is surrounded at least by the part-region.

7. The method of claim 1, wherein the capsule is provided in such a manner that negative pressure is generated in an interior space of the capsule that is configured for receiving the powder.

8. The method of claim 1, wherein a connection region of the blade airfoil in which the latter is connected to the blade root is produced from the first material and/or from the second material.

9. The method of claim 1, wherein a blade root face of the blade root at which the latter is connected to the blade airfoil, is smoothed by a subtractive method and/or by an electrolytic method prior to being connected.

10. The method of claim 1, wherein the at least one thermal input method comprises hot isostatic pressing.

11. The method of claim 1, wherein the blade airfoil, after production thereof, is subjected to local annealing in order to set a grain size distribution.

12. The method of claim 1, wherein the blade root and the blade airfoil, after connecting, are subjected to a common age annealing.

13. The method of claim 1, wherein the blade root is produced in that a body from the first material is provided, forged, annealed for homogenization, and is subsequently shaped into the blade root.

14. The method of claim 1, wherein a TiAl alloy is provided as the first material.

15. The method of claim 14, wherein the TiAl alloy comprises a γ-TiAl alloy.

16. The method of claim 1, wherein a TiAl alloy is provided as the second material.

17. The method of claim 16, wherein the TiAl alloy, apart from Ti and Al, comprises as further alloy component one or more of W, Mo, Nb, Co, Hf, Y, Zr, Er, Gd, Si, C.

18. The method of claim 14, wherein a TiAl alloy is provided as the second material.

19. A blade for a turbomachine, wherein the blade is obtained by the method of claim 1.

20. A turbomachine, wherein the turbomachine comprises the blade of claim 19.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0041] The single FIGURE shows a schematic perspective view of a blade according to the invention for a turbomachine.

DETAILED DESCRIPTION OF EMBODIMENT OF THE INVENTION

[0042] The FIGURE shows a blade 10 for a turbomachine for an aircraft engine. As in the present exemplary embodiment, the blade 10 can be configured as a rotor blade for a rotor main body that is not illustrated in more detail here. Alternatively, however, the blade 10 could also be configured as a guide vane of a guide vane apparatus, for example.

[0043] A blade root 14 of the blade 10 has a first platform region 28 and is in the present case produced from a first material that is formed from a γ-TiAl alloy, wherein the γ-TiAl alloy can be a TNM-TiAl alloy. The blade root 14 herein is shaped from a forged body, annealed for homogenization, from the first material.

[0044] The FIGURE furthermore shows a capsule 18 which has an interior space 22 that is filled with a metallic powder 12. The capsule 18 has a second platform region 30, is disposed on a blade root face 16 on the first platform region 28 of the blade root 14, and in the present exemplary embodiment imparts a shape to a blade airfoil 24 of the blade 10. The capsule 18 is formed by a generative production method, in the present exemplary embodiment by electron beam melting, from a powder bed (not illustrated in more detail here) that is filled with the powder 12. The capsule 18 is constructed layer-by-layer and directly on the blade root face 16 of the blade root 14. On account thereof, the two platform regions 28, 30 are connected to form one platform 32, and the blade root 14 is thus connected to the blade airfoil 24. The platform 32 herein can be a so-called inner shroud. In order for a particularly durable connection between the capsule 18 and the blade root 14 to be produced, the blade root face 16 and thus the first platform region 28, prior to connecting, has been smoothed by an electrolytic method.

[0045] In order for the construction of the capsule 18 on the blade root 14 (on the blade root face 16) to be accelerated, the powder 12 prior to the production of the capsule has been heated to a heating temperature which is below a sintering temperature of the powder 12. On account thereof, sintering of the powder 12 while producing the capsule 18 is possible at further input of energy that is only minor. Filling of the interior space 22 of the capsule 18 with the powder 12 is performed by the generative production method in that at least a part-region 20 (illustrated with dashed lines in the FIGURE) of the capsule 18 has been produced from the powder 12 layer-by-layer as a hollow section that is closed on the circumferential side. Herein, a part-quantity of the powder 12 from the powder bed has been surrounded by the part-region 20 and been enclosed in the capsule 18 during the construction of the capsule 18. Moreover, in order for any oxidation processes to be reduced and in order for the powder 12 to be compressed during the production of the capsule 18, negative pressure has been generated in the interior space 22 of the capsule 18.

[0046] The powder 12 is in the present case formed from a second material which is different from the first material. The second material is configured as a TiAl alloy which apart from Ti and Al comprises tungsten (W) as the further alloy component. The TiAl alloy can also comprise other or a plurality of elements from the group of W, Mo, Nb, Co, Hf, Y, Zr, Er, Gd, Si, and C, in order for the material properties of the powder 12 and thus of the blade airfoil 24 that is to be produced therefrom to be set as precisely as possible.

[0047] Producing and shaping the blade airfoil 24 from the capsule 18 that is filled with the powder 12 is performed by a thermal input method which in the present exemplary embodiment corresponds to hot isostatic pressing. Diffusion welding of a connection region 26 of the blade airfoil 24 and of the blade root 14 on the blade root face 16, and simultaneously a consolidation of the powder 12 that is enclosed in the interior space 22 of the capsule 18 arise thereby. The connection region 26 herein is assigned to both the blade airfoil 24 as well as the capsule 18, especially since the blade airfoil 24 in the thermal input method is formed from the capsule 18 and the powder 12 that is contained in the interior space 22 of said capsule 18.

[0048] The blade airfoil 24, after the production thereof, in order for a distribution of grain size to be set is subjected to local annealing. Furthermore, the blade root 14 and the blade airfoil 24, after connecting, are subjected to common age annealing, in order for targeted precipitation hardening to be initiated.

[0049] The blade 10 can now be fixed to the rotor main body (not shown here) by joining the blade root 14, for example by way of a push-fit connection.

[0050] In summary, the method proposed enables the use of a plurality of materials and thus of dissimilar TiAl alloys for the production of the blade 10. The dissimilar material properties of the respective materials in the blade 10 can thus also be utilized in a targeted manner. A flexible selection of materials is thus possible in the production of the blade root 14 and of the blade airfoil 24, and the overall blade 10, on account thereof, is capable of being designed and produced in a particularly precise manner in terms of the stresses to be expected. The blade airfoil 24, on account of being produced from the capsule 18 that is filled with the powder 12, can be provided with particularly good creep properties. This would not be possible by virtue of requirements pertaining to a minimum ductility of the blade 10, if the latter in a manner known from the prior art were only formed from one material.

[0051] On account of the method described, the blade 10, by consolidating the powder 12 in the capsule 18 and on account of the diffusion welding of the latter on the blade root 14 that is produced by forging, can be configured as a graduated component from various TiAl materials. The capsule 18 herein can be constructed in situ on the blade root 14, and the blade airfoil 24 can be generated by hot isostatic pressing (HIP) from the capsule 18 that is filled with the powder 12.

[0052] Novel high-temperature resistant and high-alloyed TiAl alloys are considered to be particularly brittle. On account thereof, the design of a connection of the blade root 14 to the rotor main body which can also be referred to as a disk is very difficult in terms of any stresses and sustainable plastic deformations in a contact region between the blade root 14 and the disk, and in the blade root 14 per se. Since the blade root 14 is exposed to lower temperature stresses but to higher tension than the blade airfoil 24, but the blade airfoil 24 is to withstand the highest creep stresses, this leads to mechanical issues in design and production. The reason lies in that the creep resistance can only be increased at the cost of ductility.

[0053] These issues can at least be reduced by using dissimilar materials for the blade root 14 and the blade airfoil 24. The use of dissimilar TiAl materials of which the mechanical properties are adapted in an optimal manner to the local requirements enables the implementation in terms of construction of mechanically separable connections between the blade and the disk, while maintaining the weight advantage of TiAl. The blade root 14 and the blade airfoil 24 which in each case can be produced from dissimilar TiAl materials, by hot isostatic pressing are connected by an at least partially powder-metallurgical production process by in situ diffusion welding in the thickest cross section on the blade root face 16 of the blade root 14 and in the connection region 26. Mutually dissimilar microstructures which contribute toward meeting the requirements pertaining to the resilience of the blade 10 are set in both parts, that is to say in the blade root 14 and in the blade airfoil 24, by a corresponding heat treatment (annealing, age annealing) of the blade 10 that is thus achieved. The blade root 14 in this instance has particularly high ductility and strength, offset by low creep resistance. By contrast, the blade airfoil 24 has a particularly high creep resistance and consistent strength up to a temperature of up to 900° C., at the cost of strength at low temperature and of low ductility. TiAl alloys having high proportions of W, Mo, Nb, Co, Hf, Y, Zr, Er, Gd, Si, C can be used as the second material for the production of the blade airfoil 24, without any requirements pertaining to ductility of the blade root 14 being undershot.

LIST OF REFERENCE NUMERALS

[0054] 10 Blade [0055] 12 Powder [0056] 14 Blade root [0057] 16 Blade root face [0058] 18 Capsule [0059] 20 Part-region [0060] 22 Interior space [0061] 24 Blade airfoil [0062] 26 Connection region [0063] 28 First platform region [0064] 30 Second platform region [0065] 32 Platform