METHOD FOR PRODUCING A BLADE FOR A TURBOMACHINE

Abstract

Disclosed is a method for producing a blade comprising a blade airfoil and a blade root for a turbomachine. The method comprises providing a first workpiece based on a first material and a second workpiece based on a second material which is different from the first material and has a higher temperature resistance than the first material; and connecting the first workpiece and the second workpiece by friction welding to form a composite component having a first region of the first material, and a second region of the second material. Optionally upon material-subtracting further processing, the first region forms the blade root, and the second region forms the blade airfoil.

Claims

1. A method for producing a blade comprising a blade airfoil and a blade root for a turbomachine, wherein the method comprises: providing a first workpiece based on a first material; providing a second workpiece based on a second material which is different from the first material and has a higher temperature resistance than the first material; connecting the first workpiece and the second workpiece by friction welding to form a composite component having a first region of the first material, and a second region of the second material; the first region forming the blade root, and the second region forming the blade airfoil, optionally upon material-subtracting further processing.

2. The method of claim 1, wherein the first material is a first titanium aluminide alloy (TiAl).

3. The method of claim 2, wherein the second material with higher temperature resistance is a second titanium aluminide alloy (HT-TiAl) which has a lower elongation at break than the first titanium aluminide alloy (TiAl).

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

5. The method of claim 4, wherein a mutual relative movement of the first workpiece and of the second workpiece in the orbital friction welding describes an elliptic shape.

6. The method of claim 1, wherein a mutual relative movement of the first workpiece and of the second workpiece in the friction welding has a maximum amplitude of at least about 0.1 mm and at most about 5 mm.

7. The method of claim 1, wherein a mutual relative movement of the first workpiece and of the second workpiece in the friction welding is periodic and has a frequency f of at least about 25 Hz and at most about 125 Hz.

8. The method of claim 6, wherein a mutual relative movement of the first workpiece and of the second workpiece in the friction welding is periodic and has a frequency f of at least about 25 Hz and at most about 125 Hz.

9. The method of claim 1, wherein the first workpiece and the second workpiece in the friction welding, while the first workpiece and the second workpiece are moved relative to one another, are pressed against one another at a surface pressure of at least about 50 MPa and at most about 250 MPa.

10. The method of claim 6, wherein the first workpiece and the second workpiece in the friction welding, while the first workpiece and the second workpiece are moved relative to one another, are pressed against one another at a surface pressure of at least about 50 MPa and at most about 250 MPa.

11. The method of claim 1, wherein post-compressing for a period of at least about 10 s and at most about 300 s takes place subsequently to the friction welding.

12. The of claim 1, wherein post-compressing takes place subsequently to the friction welding at a surface pressure that is at least as high as a surface pressure during the friction welding.

13. The of claim 1, wherein post-compressing takes place subsequently to the friction welding at a surface pressure that is at least about 10% higher than a surface pressure during the friction welding.

14. The method of claim 1, wherein a joint area between the first workpiece and the second workpiece is preheated to a temperature above a brittle-ductile transition of at least one of the two materials.

15. The method of claim 1, wherein the first workpiece and the second workpiece in the friction welding are kept in a protective atmosphere at least in a region about a joint area between the first workpiece and the second workpiece.

16. The method of claim 1, wherein the composite component after the friction welding is heat-treated at a temperature of at least about 800 C.

17. The method of claim 1, wherein after the friction welding the blade root in a material-subtracting further processing is machined from the first region.

18. The method of claim 1, wherein after the friction welding the blade airfoil in a material-subtracting further processing is machined from the second region.

19. The method of claim 18, wherein after the friction welding the blade airfoil in a material-subtracting further processing is machined from the second region.

20. A blade having a blade airfoil and a blade root for a turbomachine, obtained by the method of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In the appended drawings,

[0039] FIG. 1 shows a composite component in an intermediate step of the production method according to the invention;

[0040] FIG. 2 shows the blade that has subsequently been machined in a material-subtracting manner from the composite component according to FIG. 1;

[0041] FIG. 3 shows the production of the composite component according to FIG. 1 by means of friction welding.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0042] The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description in combination with the drawings making apparent to those of skill in the art how the several forms of the present invention may be embodied in practice.

[0043] FIG. 1 shows a composite component 1 which is made up of a first region 2a and of a second region 2b. The first region is provided by a first titanium aluminide alloy, a so-called -TiAl. The second region 2b is also provided by a titanium aluminide alloy which in terms of the creep behavior thereof is however designed for higher temperatures, the brittle-ductile transition of said second region 2b being at a higher temperature than that of the first alloy. Conversely, the ductility of the second alloy is lower, thus having a lower elongation at break than the first alloy (cf. also the details of the explanations in the introduction to the specification).

[0044] The second alloy is thus indeed suitable for the use in high-temperature conditions such as arise in the gas duct of a turbine, in particular of a jet engine (on the blade airfoil). However, by virtue of the brittleness the second alloy does not meet the structural-mechanical requirements which by virtue of the centrifugal forces apply in the region of the blade root of a rotor vane. A material failure could arise at that point by virtue of the reduced elongation at break.

[0045] According to the invention, the composite component 1 is thus produced, the first region 2a of the latter in this instance forming the blade root, and the second region 2b of said composite component 1 forming the blade airfoil. The first titanium aluminide alloy is more ductile and thus also better tuned to the requirement profiles in the blade root where in turn the temperatures are lower than in the region of the blade airfoil.

[0046] The blade according to FIG. 2 is produced by a material-subtracting further processing, for example electrochemically or by milling, from the composite component according to FIG. 1, the production of the latter being explained in detail hereunder. The first region 2a in this instance forms the blade root, the second region 2b forming the blade airfoil.

[0047] FIG. 3 shows how the first workpiece 30a and the second workpiece 30b are friction-welded together in order for the composite component 1 to be produced. The relative movement of the orbital friction welding describes a circular path; the amplitudes x and y are thus of equal size, being about 1 to 2 mm. In general however, the workpieces 30a,b can of course also be moved relative to one another on an elliptic path, or joined by means of linear friction welding, respectively, reference being made explicitly to the introduction to the specification.

[0048] The amplitude of the relative movement is about 60 to 80 Hz, and the two workpieces 30a,b meanwhile are pressed against one another at a surface pressure of about 100 MPa. The workpieces 30a,b are subsequently post-compressed for approximately 30 seconds, specifically at a surface pressure of about 120 MPa. The workpieces 30a,b prior to or during the friction welding, respectively, are preferably preheated to a temperature above the brittle-ductile phase transition temperatures of both materials, said preheating preferably being by inductive heating. The composite component 1 after a heat treatment at about 1000 C. for several hours is fed to the material-subtracting further processing as has been described above.

LIST OF REFERENCE NUMERALS

[0049] First workpiece 30a

[0050] Second workpiece 30b

[0051] Composite component 1

[0052] First region 2a

[0053] Second region 2b