METHOD FOR PRODUCING BLADES FROM Ni-BASED ALLOYS AND BLADES PRODUCED THEREFROM

Abstract

The present invention relates to a method for producing a component of a turbomachine from a metal alloy as well as a correspondingly produced component, wherein the method includes defining at least one first component region that will have a first property profile, and at least one second component region that will have a second property profile which is different from the first property profile; providing at least one powder of the metal alloy or several different powders of constituents of the metal alloy; additive manufacture of the component from the at least one powder, wherein the powder is melted for cohesive joining of the powder particles to each other and to a substrate or to an already produced part of the component.

Claims

1. A method for producing a component of a turbomachine from a metal alloy, which comprises the following steps: defining at least one first component region having a first property profile, and at least one second component region having a second property profile which is different from the first property profile; providing at least one powder of the metal alloy or several different powders of constituents of the metal alloy; additive manufacturing of the component from at least one powder, wherein the powder is melted for cohesive joining of the powder particles to each other and to a substrate or to an already produced part of the component, and wherein the powder particles for the formation of the first component region and the powder particles for the formation of the second component region are different, and/or are additively deposited under such different conditions that different structures of the deposited material are produced in the first component region and in the second component region.

2. The method according to claim 1, wherein during the additive manufacture, the component is built up layer-by-layer onto a substrate or a previously produced part of the component, wherein a layer-by-layer construction by layerwise deposition welding or layerwise melting of powder material with an energy-rich beam and layerwise solidifying of the molten powder.

3. The method according to claim 2, wherein the energy-rich beam is a laser beam or an electron beam.

4. The method according to claim 1, wherein, prior to the melting, a preheating of the powder material is carried out by radiant heating or inductive heating.

5. The method according to claim 1, wherein the different conditions for melting the powder comprise at least one item from the following group: different heating energy, different beam energy, different melting temperatures, different melting rates, different preheating times, different holding times in the molten state, different cooling conditions, different cooling rates, different temperature gradients, different ambient pressures, and different deposition rates.

6. The method according to claim 1, wherein the component is formed of a metal alloy of the same chemical composition in the first component region and in the second component region.

7. The method according to claim 1, wherein the different powder particles and/or the different conditions for melting the powder during the production of the first and/or the second component region are varied over the corresponding first and/or second component region and/or in the transition region between the first and second component region, so that a gradient of material with varying property profile is deposited in the corresponding first and/or second component region and/or in the transition region.

8. The method according to claim 1, wherein the property profile of the first component region has an improved fatigue strength than that in the second component region and/or in that the property profile in the second component region has a higher creep resistance than in the first component region.

9. The method according to claim 1, wherein the component is a blade of a turbomachine, in particular a rotating blade, wherein the first component region comprises the blade root and the second component region comprises the region of an inner and/or outer shroud and/or the region of the blade element and/or the transition region between shroud and blade element.

10. The method according to claim 1, wherein the component is formed of an Fe-, Co- or Ni-based superalloy.

11. The method according to claim 1, wherein a fine-grained structure with fine deposition is formed in the first component region, and/or a coarse-grained structure with coarse depositions is formed in the second component region.

12. The method according to claim 1, wherein the component is made of an Fe-, Co- or Ni-based superalloy and is fabricated in one piece by additive manufacture, wherein the component comprises at least one first component region that has a first property profile, and at least one second component region that has a second property profile, which is different from the first property profile, wherein first and second component regions have different micro structural formations.

13. The method according to claim 12, wherein the component is a blade of a turbomachine wherein the first component region comprises the blade root and the second component region comprises the region of an inner and/or outer shroud and/or the region of the blade element and/or the transition region between shroud and blade element.

14. The method according to claim 12, wherein the property profile of the first component region has an improved fatigue strength than that in the second component region and/or in that the property profile in the second component region has a higher creep resistance than that in the first component region.

15. The method according to claim 12, wherein a fine-grained structure with fine depositions is formed in the first component region, and/or a coarse-grained structure with coarse-grained depositions is formed in the second component region.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0017] The appended drawings show in a purely schematic way in:

[0018] FIG. 1, a schematic representation of a device for the additive manufacture of components on the example of selective laser melting; and in

[0019] FIG. 2, an illustration of a turbine blade that is manufactured corresponding to the method according to the invention.

DESCRIPTION OF THE INVENTION

[0020] Further advantages, characteristics and features of the present invention will become apparent in the following detailed description of examples of embodiment. Of course, the invention is not limited to these exemplary embodiments.

[0021] In a purely schematic representation, FIG. 1 shows a device 1, as can find use, for example, for selective laser melting for the additive manufacture of a component, and, in particular, a rotating blade The device 1 comprises a lift table 2, on the platform of which is disposed a semi-finished product or pre-product 3, onto which material is deposited layer by layer in order to produce a three-dimensional component in the form of a rotating blade for a turbomachine. For this purpose, powder 10 that is found in a powder supply container above a lift table 9, is moved by means of a slider 8, layer by layer, over the pre-product 3 and subsequently joined to the already present pre-product 3 by melting via the laser beam 13 of a laser 4. The powder material is joined to the pre-product 3 in a powder layer via the laser 4 according to the desired contour of the component to be fabricated, so that any three-dimensional form can be produced. Correspondingly, the laser beam 13 is guided over the powder bed 12 in order to melt powder material via different impact points on the powder bed corresponding to the contour of the three-dimensional component in the cutting plane corresponding to the sectional plane that has been produced, and to join to the already produced part of a component or to an initially provided substrate. In this way, the laser beam 13 can be guided over the surface of the powder bed 12 by a suitable deflection unit and/or the powder bed could be moved opposite the laser beam 13.

[0022] In order to avoid undesired reactions with the surrounding atmosphere during melting or sintering, the process can take place in an enclosed space that is provided by a housing 11 of the device 1, and an inert gas atmosphere can also be provided in order to avoid oxidation of the powder material, for example, and the like, during the deposition. For example, nitrogen, which is provided via a gas supply line (not shown), is used as the inert gas.

[0023] Instead of the inert gas, another process gas could also be used, if, for example, a reactive deposition of the powder material is desired.

[0024] Apart from this, other kinds of radiation are also conceivable, such as electron beams or other particle beams, or light beams that are used in stereolithography, for example.

[0025] For establishing the desired temperatures in the produced component 3 and/or in the powder bed 12, an electrical resistance heater with a resistance heating control 5 and an electrical heating filament 6 is provided in the lift table, so that the powder bed 12 and the component 3 can be preheated to a desired temperature by corresponding heating from below, and/or a desired temperature gradient can be established, in particular relative to the just processed layer at the surface of the powder bed. In a similar way, heating is provided by a heating apparatus from the top of the powder bed 12 and the already created component 3, which, in the exemplary embodiment shown, is formed by an induction heater having an induction coil 14 and an induction heating control 15. The induction coil 14 in this case surrounds the laser beam 13 and can be moved, as needed, parallel to the surface of the powder bed 12 corresponding to the laser beam 13.

[0026] Instead of the induction heater shown, any other kind of heater that enables a heating of the powder bed 12 and/or the already produced component 3 from the top also can be provided, such as, for example, radiant heating devices such as infrared heaters and the like. In the same way, the resistance heater 5, 6 can also be replaced by other suitable kinds of heating that make possible a heating of the powder bed 12 and the already produced component 3 from below. Apart from this, additional heating means surrounding the already produced component 3 and/or the powder bed 12 can be provided, in order to make possible a lateral heating of the powder bed 12 and/or the already produced component 3.

[0027] In addition to heating means, cooling means or combined heating/cooling means may also be provided, in order to be able to also carry out a targeted cooling, in addition to a heating of the already produced component 3 and the powder bed 12, in order to thereby be able to adjust and influence in a targeted manner the temperature balance in the powder bed and/or the produced component 3, in particular, relative to the powder layer melted by the laser beam 13 and the solidification front at the molten powder material.

[0028] According to the invention, the component can be divided into at least two component regions that are constructed from the same material relative to the chemical composition, but are formed with different structures due to use of different powders and/or process parameters in the additive manufacture. For this purpose, when a change is made from one component region to the other component region, only a corresponding exchange of powder material and/or a change of the deposition parameters need be carried out during the conduction of the additive manufacturing process.

[0029] FIG. 2 shows a blade 21 of a turbomachine having a blade element 23 and a blade root 23 as well as an inner shroud 24 arranged between blade element 23 and blade root 22. The blade 21 is formed, by way of example, of an Ni-based superalloy, as is known, for example, under the trade name IN 718. Of course, other Ni-based superalloys or other high-temperature alloys, such as, for example, Fe-based superalloys or Co-based superalloys are also conceivable.

[0030] The blade 21 is additively formed from a powder material of the Ni-based superalloy by selective laser beam melting, for example with a device from FIG. 1, wherein, layer by layer, corresponding to the cross section of the blade 21, the blade 21 is formed in a corresponding structural layer on the already manufactured part of the blade 21 by melting and solidifying the powder of the Ni-based superalloy. In this way, the entire blade 21 is constructed, layer by layer, from the Ni-based superalloy.

[0031] According to the invention, however, two component regions of the blade 21 are formed in different ways in order to produce different structural formations and thus different property profiles in the two component regions.

[0032] The first component region is formed by the blade root 22, wherein, in this region, a structure with grains that are as fine as possible of the Ni-based superalloy containing fine-grained carbide depositions is formed in order to establish an advantageous fatigue behavior with a high fatigue strength. This can be achieved due to the fact that a finer-grained initial powder is selected for the additive manufacture of the blade root 22 than for the manufacture of the remaining part of the blade 21. Alternatively or additionally, it is also possible to suitably select the process parameters for the additive manufacture, such as, e.g., to select the build-up rate in the region of the blade root 22 higher than in the rest of the blade 21 to be formed, so that based on higher melting energy that is introduced as well as shorter residence time of the laser beam for melting the powder, and a higher cooling rate for the solidifying of the melt, more solidification nuclei are formed and thus a finer structure can be established than in the remaining region of the blade 21.

[0033] Correspondingly, the blade element 23 and/or the inner shroud 24 or the transition region between blade element 23 and inner shroud 24 can be defined as a second component region, in which, by use of a coarser initial powder and/or adjusted process parameters during the additive manufacture, e.g., with respect to a slower buildup rate with slower melting, longer residence time of the laser beam in the region of the molten powder and thus longer holding time of the powder in the molten state and slower cooling, a coarser structure with larger carbide depositions than in the first component region or additional component regions can be established, which leads to the circumstance that the creep resistance is improved.

[0034] Thus, for example, for an Ni-based superalloy in the first component region, in the region of the blade root 22, particle sizes of up to a maximum of 500 m, preferably up to a maximum of 100 m can be established, while the carbide depositions can have a maximum size of 30 m, preferably a maximum of 10 m, whereas in the second component region, in the region of the blade element, particle sizes of more than 500 m are possible. In this case, the particle size can be determined as the mean particle size according to known methods for determining particle sizes or as the maximum dimension of the particles in one direction.

[0035] Although the present invention has been described in detail on the basis of the exemplary embodiments, it is obvious to the person skilled in the art that the invention is not limited to these exemplary embodiments, but rather that modifications are possible in such a way that individual features are omitted or other types of combinations of features can be realized, without leaving the scope of protection of the appended claims. In particular, the present disclosure encompasses all combinations of the individual features shown in the different examples of embodiment, so that individual features that are described only in conjunction with one exemplary embodiment can also be used in other exemplary embodiments or combinations of individual features that are not explicitly shown can also be employed.