METHOD FOR PRODUCING A BLADE FOR A TURBOMACHINE

Abstract

Disclosed is a method for producing a blade for a turbomachine, in particular for an aero engine. The method comprises providing at least one blade airfoil with a first platform region and at least one blade root with a second platform region and joining the blade airfoil and the blade root at the respective platform regions by a friction welding method at a common joint region of the platform regions, the blade airfoil and the blade root being made of materials which are different from each other. Also disclosed is a blade which is and/or can be obtained by such a method.

Claims

1. A method for producing a blade for a turbomachine, wherein the method comprises providing at least one blade airfoil with a first platform region and at least one blade root with a second platform region and joining the blade airfoil and the blade root at respective platform regions by a friction welding method at a common joint region of the platform regions, the blade airfoil and the blade root being made of materials which are different from each other.

2. The method of claim 1, wherein the friction welding method comprises a linear friction welding method.

3. The method of claim 1, wherein the friction welding method comprises an orbital friction welding method.

4. The method of claim 1, wherein the blade airfoil is made of a first TiAl alloy.

5. The method of claim 4, wherein the first TiAl alloy comprises, as further alloying constituent in addition to Ti and Al, one or more of W, Mo, Nb, Co, Hf, Y, Zr, Er, Gd, Si, C.

6. The method as claimed in claim 4, wherein the blade root is made of a second TiAl alloy which is different from the first TiAl alloy.

7. The method as claimed in claim 5, wherein the blade root is made of a second TiAl alloy which is different from the first TiAl alloy.

8. The method of claim 6, wherein the blade root is produced by providing a body made of the second TiAl alloy, which is then forged, homogenization-annealed and subsequently shaped into the blade root, the blade root being smoothed at least in some regions.

9. The method of claim 1, wherein at least the blade airfoil is built up by a thermo-mechanical production method or an additive production method.

10. The method of claim 9, wherein at least the blade airfoil is built up by one or more of selective laser melting, selective laser sintering, electron beam melting and laser deposition welding and/or by hot-isostatic pressing of a capsule filled with material powder.

11. The method of claim 1, wherein at least one of the blade root and the blade airfoil is heat-treated prior to joining.

12. The method of claim 1, wherein after the blade airfoil has been joined to the blade root the joint region is subjected to a localized heat treatment.

13. The method of claim 1, wherein after the blade airfoil has been joined to the blade root the entire blade is subjected to a precipitation heat treatment.

14. A blade for a turbomachine, wherein the blade comprises a blade airfoil made of a first material and a blade root made of a second material that is different from the first material, the blade airfoil being joined directly to the blade root by a friction welding method to form a common joint region.

15. The blade of claim 14, wherein the blade airfoil is made of a first TiAl alloy.

16. The blade of claim 15, wherein the first TiAl alloy comprises, as further alloying constituent in addition to Ti and Al, one or more of W, Mo, Nb, Co, Hf, Y, Zr, Er, Gd, Si, C.

17. The blade of claim 14, wherein the blade root is made of a second TiAl alloy which is different from the first TiAl alloy.

18. The blade of claim 15, wherein the blade root is made of a second TiAl alloy which is different from the first TiAl alloy.

19. A turbomachine, in particular an aero engine, wherein the turbomachine comprises at least one blade that is obtained by the method of claim 1.

20. A turbomachine, in particular an aero engine, wherein the turbomachine comprises the blade of claim 14.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0032] In this context, the single FIGURE is a schematic perspective view of a blade, produced by a method according to the invention, for a turbomachine.

[0033] DETAILED DESCRIPTION OF EMBODIMENT OF THE INVENTION The FIGURE shows a blade 10 for a turbomachine (not shown further here), which can for example be configured as an aero engine. The blade 10 can for example be designed as a rotor blade for a blade ring. Alternatively, the blade 10 can also be designed as a stator vane.

[0034] In the present exemplary embodiment, a blade airfoil 16 with a first platform region 24 is made of a first TiAl alloy which for example comprises tungsten (W) as further alloying constituent in addition to titanium (Ti) and aluminum (Al). In order to make the blade airfoil 16, use can be made, for example, of an additive production method, for example selective laser melting, selective laser sintering, electron beam melting and/or laser deposition welding, and/or hot-isostatic pressing of a capsule filled with material powder. Also provided is a blade root 12 with a second platform region. In the present exemplary embodiment, the blade root 12 is produced by forging and subsequent homogenization annealing at a temperature of 1150° C. for eight hours.

[0035] In the present case, the blade root 12 is made of a second TiAl alloy that is different from the first TiAl alloy. Thus, the blade airfoil 16 and the blade root 12 respectively consist of different materials. In the present case, the blade root 12 is produced by first providing a body of the second TiAl alloy which was forged, homogenization-annealed and then shaped into the blade root 12. Subsequently, the blade root 12 is smoothed at least in certain regions, in the present case on the second platform region 26. The smoothing at least in certain regions can for example be electrolytic polishing or a chip-removing smoothing method such as milling or grinding. In addition to the blade root 12, the blade airfoil 16 can also undergo such a smoothing in certain regions. In the present case, the first platform region 24 of the blade airfoil 16 has also been smoothed. If both the blade root 12 and the blade airfoil 16 undergo smoothing, prior to joining, at respective joining regions (of the blade root 12 and of the blade airfoil 16) that at least partially form a later joint region 18, it is possible to obtain a particularly durable join.

[0036] The present case shows how the blade airfoil 16 is joined directly, by a friction welding method, to the blade root 12 at the common joint region 18. In the present exemplary embodiment, the joint region 18 is that region at which the two platform regions 24, 26 are joined by the friction welding method to give a platform 28. In the present case, the platform 28 is an inner shroud of the blade 10.

[0037] Both the blade root 12 and the blade airfoil 16 were heat-treated prior to joining, this not being shown in greater detail here. In the present exemplary embodiment, the friction welding method is a combination of a linear friction welding method and an orbital friction welding method.

[0038] The combination consists in the fact that, during the friction welding method, the blade root 12 is subject to a linear movement 20 (it is moved back-and-forth in linear fashion), while the blade airfoil 16 follows a closed path movement 22. These combinations, which, so to speak, represent superpositions of the movements, establish a movement path (relative movement between the blade root 12 and the blade airfoil 16). After joining, the joint region 18 undergoes localized heat treatment (not shown here). Furthermore, after the blade airfoil 16 has been joined to the blade root 12, the entire blade 10 undergoes precipitation heat treatment (not shown here either) in order to reduce any stresses within the blade 10.

[0039] In summary, the invention makes it possible to join the brittle TiAl blade root 12 to a rotor disk by means of a mechanical connection means despite the fact that this connection has many problems in prior art systems (e.g. slot-type connection). In order to reduce this problem in the mechanical connection point, according to the invention described here the blade 10 on the blade root 12 is made of a more ductile alloy than the blade airfoil 16. In addition, the blade airfoil 16 is joined to the blade root 12 which is made of a different alloy, wherein both materials belong to the class of the TiAl alloys. In that context, a new, high-temperature-resistant and high-alloyed TiAl alloy is friction-welded to a known TiAl material that satisfies the necessary ductility requirements. The blade root 12 and the blade airfoil 16 can be produced and heat-treated independently of one another, depending on the most economical production route, or can even be end-heat-treated in order to finally be friction-welded together and then machined to their final contour.