EP2051829A1

EP2051829A1 - Method of producing or repairing turbine or engine components, and a component, namely a turbine or engine component

Info

Publication number: EP2051829A1
Application number: EP07722486A
Authority: EP
Inventors: Andreas Vossberg; Hans Joachim RÖSLER; Sebastian Piegert
Original assignee: MTU Aero Engines GmbH
Current assignee: MTU Aero Engines AG
Priority date: 2006-06-08
Filing date: 2007-05-31
Publication date: 2009-04-29
Also published as: WO2007140748A1; JP5054100B2; JP2009540173A; US20100291405A1; US8555500B2; DE102006026704A1

Abstract

The invention relates to a method of producing or repairing single-crystalline turbine or engine components, in which a braze filler metal is heated to a temperature which is greater than or equal to the melting temperature of this braze filler metal. The molten mass, thus produced, of the braze filler metal is then introduced into a crack formed in the turbine or engine component or into a gap formed between two turbine or engine components. The temperature of the braze filler metal is then controlled in a non-isothermal manner during an epitaxial solidification process of this braze filler metal. This method, which can be used, for example, in connection with turbine or engine components made of a nickel-base alloy, has the advantage over conventional methods that it permits a quicker brazing repair of turbine or engine components, in particular in the case of large gap or crack widths, and in addition this method can bring about a state in which the repaired regions again have a single-crystalline structure and thus have the corresponding high mechanical strength, oxidation resistance and re-melting temperature.

Description

Process for the manufacture or repair of turbine or engine components, and component, namely turbine or engine component

The invention relates to a method for producing or repairing turbine or engine components and a component, namely turbine or engine component.

US Pat. No. 5,732,467 discloses a method for repairing surface cracks, wherein the substrate consisting of a superalloy has a directionally solidified structure. The cleaned crack is filled with the substrate material. The coated crack is then exposed to elevated temperature and isostatic pressure for a period of time without changing the microstructure of the substrate.

No. 5,666,643 discloses a method for repairing components of cobalt- and nickel-based superalloys by means of soldering. In this method, a two-part solder material is used, one component of which forms the (actual) solder alloy, and the other component of which is formed by particles which are refractory and either monocrystalline, directionally solidified or polycrystalline. In this design, the microstructure of the repaired crack deviates from that of the substrate, resulting in strength impairments within the filled cracks, particularly when positioned in areas of stress concentrations.

As a rule, similar problems always arise in repair processes in which the microstructure of the substrate is not restored, for example in connection with the processes known from US Pat. No. 4,381,944 or US Pat. No. 5,437,737, in which process in each case the solder alloy with an additive material is provided to increase the strength of the filled column.

Another approach is given in the method disclosed in US 5,156,321 in that there a sintering process is used to make the repair more effective.

Two similar soldering methods are disclosed in US 4,830,934 and US 5,240,491, which are intended for polycrystalline and directionally solidified superalloys, as described, for example, in US 4,288,247. The repair system consists of at least three different metal powders. These different metal powders fulfill different functions. The metal powders of a first group are high-melt zend and have a relatively high proportion of Mo, Re and W on; These metal powders do not melt or only partly melt during the soldering process. The metal powders of a second and the remaining third group ensure a corresponding flow behavior of the soldering system. The metal powders of the second group contain B and / or Si as melting point lower, and the metal powders of the third group in this case have eutectic compositions and assist in the soldering process as a liquid phase, the decay. The solidification is brought about by an isothermal soldering operation, which is followed by a graduated diffusion cycle, but no monocrystalline filling of the gap is achieved. The modular principle allows a flexible handling of the microstructure of the gap and the mechanical properties, which quite well achieve the properties of the substrates.

A similar modular principle is disclosed in US 2002/0157737 Al. According to the disclosure there, a low melting powder, which may contain up to 1% Ti, W, Re, Mo, Nb, Hf, Pd, Pt, Ir, Ru, C, Si and / or Zr, is mixed with at least one refractory powder , The soldering temperature is 1260 ° C (10-40 min) and is again followed by a graded diffusion cycle. It seems that the creep rupture strength is close to that of the substrate.

According to the disclosure of EP 1 226 896 A2, Rene 80 powder is mixed with a ternary eutectic solder alloy containing about 15% Cr, 3.5% B and additionally up to 1.5% Fe. The mixing ratio amounts to 65:35 in favor of Rene 80. The brazing temperature is between 1175 ° C and 1215 ⁰ C and kept for about 20 min. This results in a solder seam with polycrystalline microstructure. In this case, the repair part can be applied to the component by various techniques, such as, for example, as paste, plasticine or via pre-sintered plates. Pre-sintered plates may for example be produced such that superalloy sheets are powder metallurgically produced, as disclosed in GB 2153845A.

US 6,325,871 discloses an isothermal soldering cycle by means of which components of cast superalloys can be bonded. In this case, films are used whose boron content is 1 to 3 wt .-%.

A similar process has become known from US 6,508,000 for deposits. In this publication, a soldering process limited to gap widths of up to 25 μm is temporary discloses controlled liquid phases with which turbine blades and vanes can be repaired.

Another approach is disclosed in US 6,968,991 for monocrystalline components. In this case, the solder material in the form of a viscous mass (color), which consists of solder material, additive material, binder and a carrier, applied to the previously mechanically closed and spot-welded crack whose width may be a maximum of 0.05 mm. The soldering process itself lasts up to 20 minutes and is carried out at a temperature of 1204 ° C. After a subsequent cooling to 816 ⁰ C is heated again to 1204 ⁰ C, so that the Schmelztemperaturerniedriger diffuse from the gap in the base material.

In particular, US Pat. No. 6,629,368 discloses an isothermal solder repair of monocrystalline turbine blades which appears to restore a monocrystalline structure in the soldered areas. A disadvantage of the design according to US Pat. No. 6,629,368 is that there is a risk of damage to the base material and that the process involves uneconomically long process times.

Further, US 6,629,368 discloses a method according to which an isothermal epitaxial annealing of cracks is provided on monocrystalline materials.

A disadvantage of the designs known from US Pat. No. 4,830,934 or US Pat. No. 5,240,491 or US Pat. No. 5,732,467 or US Pat. No. 5,666,643 or US Pat. No. 4,381,944 or US Pat. No. 5,437,737 is that the components do not have the original mechanical strength, oxidation resistance and reflow temperature there after repair The components are significantly deteriorated in terms of these criteria after repair.

Against this background, the invention has the object to provide a suitable for the field of aircraft engines or turbines possibility of joining and / or repair of components, by means of which the mechanical and physical properties in the joining or repair area not or at least in proportion small extent. According to the invention, a method according to claim 1 is proposed. A component according to the invention, namely a turbine or engine component, is the subject matter of claim 8 or claim 10. Preferred developments are the subject of the subclaims.

Thus, according to the invention, in particular a method, in particular high-temperature soldering, for producing or repairing, in particular monocrystalline, turbine or engine components is proposed which comprises the following steps: heating a solder to a temperature which is greater than or equal to the melting temperature of this solder ; Spend the resulting during this heating melt of the solder in a formed in the turbine or engine component crack or in a formed between two turbine or engine components gap or in a, in particular by material removal, damaged area of a turbine or drive factory component; and non-isothermal control of the temperature of the solder during an eptitaktisches Festarrungsprozesses this solder.

For the purposes of the present disclosure or invention, a solder is understood in particular to be a solder alloy, or a multicomponent soldering system comprising as components of the multi-component soldering system a solder alloy and at least one, such as exactly one or exactly two or exactly three or more three, additive material (s) identifies or consists of a solder alloy and at least one, such as exactly one or exactly two or exactly three or more than three, additive material (s).

By means of such a method, based in particular on a non-isothermal, epitaxial see solidification of a solder in a crack or gap or in a damaged area of a component or material, such as nickel-based alloy, for example, the solidification process of the solder compared to known methods in which the solidification process is isothermal, - be shortened - at least at significant gap widths, such as those which are greater than or equal to 200 microns. Especially in the case of monocrystalline substrates or monocrystalline components to be repaired, such as monocrystalline turbine or engine components or single-crystal turbine blades, the method according to the invention provides a good basis for the fact that a monocrystalline or at least one directionally solidified structure is also present in the repaired area after the repair and thus the mechanical and physical properties can be restored to a high degree. The solder can be used up, for example, in the form of a viscous paste or placed in the crack or nip or applied to the damaged areas. The viscosity can be achieved, for example, by mixing the metal powders with an organic binder. The proportion of the binder may be, for example, 5 to 15% by weight, in particular 5 to 10% by weight or 8 to 12% by weight, particularly preferably substantially 10%, of the powder mixture.

The epitaxial solidification of the solder takes place in an advantageous embodiment of the method according to the invention with or at sinking, in particular strictly monotonically decreasing, temperature of the sample or the turbine or engine component or the solder. In an advantageous design, the temperature drops linearly. The cooling or sinking of the temperature during epitaxial solidification is controlled or regulated in particular.

According to a particularly preferred development, the cooling in the method according to the invention, ie in particular in high-temperature soldering, i. also in epitaxial soldering, controlled by means of an open control in a high vacuum. In this case, for example, setpoints can be specified by means of a computer program and the actual values by means of thermocouples on the sample or on the component or on the turbine or engine component or in the area of the solder - for simplicity, hereinafter abbreviated to sample instead of the above list spoken - determined or measured. Preferably, the sample is not actively cooled, wherein the cooling is effected via a natural heat loss of the sample (radiant heat) when the heat source, in particular heating, is switched off. In order to set or control or to regulate a specific or predetermined cooling rate, it is possible to counterheat if the cooling rate is too high. The heating can again be done by radiant heat emitted by heating elements.

It should be noted that the aforementioned furnace control is only of an exemplary nature and, for example, other heat sources or heat transfers may be provided, such as, for example, when brazing under protective gas, heat transfer via gas molecules (kinetics) or inductive heat transfer during inductive soldering.

In an advantageous embodiment, the temperature decreases according to the inventive method - as mentioned - during the epitaxial solidification process, but with a lower cooling rate than it decreases after the epitaxial solidification process. For example, during the epitaxial solidification process, the cooling rates may be between 100 K / min and 0.001 K / min, preferably 20 K / min and 0.01 K / min, preferably 10 K / min and 0.01 K / min, preferably 5 K / min and 0.01 K / min, preferably 0.5 K / min and 0.08 K / min. On cooling after the epitaxial solidification process, cooling rates are particularly preferred which are less than 100 K / min, preferably less than 80 K / min, preferably less than 60 K / min, preferably less than 40 K / min, preferably less than 20 K / min , preferably less than 10 K / min, preferably less than 5 K / min, preferably less than 2 K / min, wherein the cooling rate may be constant or non-constant.

As the solder, for example, a solder alloy having a composition according to the following table can be used in the method:

or according to the following table

the latter example corresponds to commercial Lot D-15.

By BaI. In this case, it is indicated in particular that as a result of this, ie here by nickel (Ni), the sum of the weight fractions should be supplemented to 100%.

In an advantageous embodiment it can be provided that the solder has a nickel-based additive material which, for example, besides nickel, has one or more of the following elements:

or one or more of the following elements

having.

In the following, embodiments of the invention will be explained in more detail with reference to the FIGURE, without the invention thereby being restricted to these. Showing:

1 shows a temperature profile which may be given in an exemplary method according to the invention;

FIG. 2 shows exemplary compositions of materials which can be used in connection with a method according to the invention, and in particular the exemplary method according to the invention explained with reference to FIG. 1 or FIG. 3; FIG. and

FIG. 3 shows a further exemplary temperature profile, which may be given in another exemplary method according to the invention. 1 shows an exemplary temperature-time profile 1 for a solder, which may be given in the context of an exemplary soldering or repair method according to the invention or an exemplary solder repair according to the invention for nickel base materials or for turbine blades made of a nickel-based material. The nickel base material or the turbine blade made of a nickel-based material can be monocrystalline or polycrystalline or directionally solidified.

This method is explained here by way of example, according to which the nickel base material or the turbine blade has a crack or gap to be healed or to be filled or a region to be healed, which for example has a width or height of up to 500 μm.

The solder may be, for example, a nickel-based boron-containing solder. The boron serves as melting point depressant and has a high mobility in nickel. In addition, the solder may contain palladium, which is also a melting point depressant, and additionally increases the boron solubility of boron in the ternary Ni-Pd-B system. The solder can furthermore contain one, several or all of the .gamma. 'Imagers Al, Nb and Ta, so that a precipitation hardening is carried out with a suitable heat treatment following the non-isothermal epitaxial solidification process (which will be mentioned below) can and is carried out in a preferred embodiment.

With regard to exemplary brazing materials, to which an additive material may or may not be added, one of the materials may be provided, for example, which is described in DE 103 56 562 A1 of the applicant in paragraphs [0006] to [0069] or in US Pat Claims 1 to 23 are disclosed. For this purpose, the mentioned passages of DE 103 56 562 Al are incorporated by reference into the subject of the present disclosure, wherein the applicant expressly reserves the right to claim as embodiments of the present invention, embodiments in which the passages mentioned in DE 103 56 562 Al disclosed materials are provided as solders.

For example, it may be provided that the solder material has a composition according to the following table:

By BaI. In this case, it is indicated in particular that, as a result, that is to say here nickel (Ni), the sum of the weight fractions is to be supplemented to 100%.

A particularly advantageous solder composition is described in the second line of the table according to FIG. 2 (A2 solder alloy).

The solder alloy may be added to an additive material. This additive material may be formed, for example, on nickel base. It can be provided that the proportion of the additive material added to the solder alloy is greater than 20% by weight, preferably greater than 25% by weight, preferably between 20 and 60% by weight, preferably between 25 and 50% by weight .-%, preferably between 30 and 50 wt .-%, preferably between 40 and 50 wt .-%, particularly preferably 50 wt .-% of the solder. The additive material may be, for example, Rene 80, the composition of which is shown in line 3 of FIG.

As already mentioned, the substrate, i. the material to be annealed, or the turbine blade nickel-based. The substrate, i. The material to be annealed, or the turbine blade, can furthermore be polycrystalline, solidified in a columnar manner or monocrystalline. It should be noted, however, that special advantages of the method only come into play with columnar or monocrystalline materials.

The exemplary temperature-time curve 1 according to FIG. 1 refers, at least with regard to the indicated temperature and time values, by way of example to materials or substrates or turbine blades made of a monocrystalline nickel base.

Superalloy Rene N-5 or is optimized for a single crystal nickel base superalloy Rene N-5. The composition of such a nickel-base superalloy Rene N-5 is shown in Fig. 2 in the last line. It should be noted, however, that the method can also be used, for example, in a columnar solidified or monocrystalline superalloy, in particular nickel-based alloy. According to an exemplary method according to the invention, in particular a method whose course of the temperature control for the non-isothermal (ie preferably decreasing temperature) epitaxial soldering of nickel-based materials is shown in FIG. 1, first a solder is heated to a temperature, which is greater than or equal to the melting temperature of this solder. In particular, it is then heated up to a temperature at which the solder is partially or completely molten.

Subsequently, the melt of the solder produced during this heating is then transferred into a crack formed in the turbine or engine component or into a gap formed between two turbine or engine components or onto an area to be repaired. This can also be done temporally parallel or temporally overlapping for heating, but alternatively also after heating.

As the temperature-time course 1 of FIG. 1 shows, the heating is there so that is heated to a temperature which is between 1200 ° C and 126O ⁰ C to completely melt the solder and the gap with melt to expire. The area of the heating is illustrated in FIG. 1 by the reference numeral 10. Complete dissolution can be achieved, for example, by holding the melting temperature for 15-45 minutes. This is illustrated in FIG. 1 by the region 12. Alternatively, however, it may also be provided that such a holding of the melting temperature is dispensed with, or that the holding of the temperature which takes place after the heating and before the eptitaktischen solidification process, for a period of time which differs from the aforementioned period of time. If such a holding of the temperature is provided, however, it is provided in particular that the holding of the temperature lasts shorter than the subsequent epitaxial solidification process. For example, it may be provided that the holding of the temperature is less than 50%, preferably less than 40%, preferably less than 30%, preferably less than 20%, preferably less than 10%, preferably less than 5%, preferably less than 3% , preferably less than 1% of the time taken by the epitaxial solidification process or a given cooling claimed.

In the already mentioned, subsequent epitaxial solidification process of the solder, the temperature of the solder is non-isothermally guided or controlled. Thus, in particular, the epitaxial solidification process is performed non-isothermally by continuous from the melting temperature -. B. in the form of a ramp - is cooled, so that the material in the gap or crack homogeneous, ie without eutectic islands, epitaxially solidified. Not that one- Isothermal epitaxial solidification takes place in the exemplary method according to the invention, the temperature-time course 1 is shown in Fig. 1, within 2 to 25 hours. In this example, while the temperature of the solder is cooled to 1050 ° C to 1200 ⁰ C.

The non-isothermal temperature control during epitaxial solidification is shown schematically in FIG. 1 by the region with the reference numeral 14.

The described process or the non-isothermal epitaxial solidification according to the exemplary method according to the invention has in particular three effects:

The first effect is that the boron diffuses into the base material, similar to the isothermal epitaxial solidification processes. The second effect is that the boron solubility in nickel is increased up to a temperature of 1093 ° C. The third effect is that melt-point-lowering elements accumulate in the melt and thus take into account a lowering of the liquidus temperature.

After the epitaxial solidification - as indicated in the area 16 - the temperature is returned to ambient temperature, which can be controlled or not controlled.

In particular, the embodiment shows a structural, non-isothermal solder repair of single-crystal turbine blades. When using this soldering process, the repaired areas again have a monocrystalline structure and thus the associated high mechanical strength, oxidation resistance and remelting temperature. The temperature resistance is thus - for example, in contrast to the design according to US 6,629,368 Bl - not isothermal, but non-isothermal with decreasing temperature, so that the soldering process is significantly accelerated.

According to the state of the art, turbine components made of monocrystalline nickel-base alloys which exhibit thermal fatigue cracks and material removal as operational damage images do not have a monocrystalline structure when using the soldering processes previously established in the field of aircraft turbines in the repaired areas. As a result, they do not have the original mechanical strength, oxidation resistance and remelt temperature after the repair. According to the embodiment explained with reference to FIG. In contrast to the exemplary embodiment of the present invention, however, the monocrystalline structure and thus also the mechanical and physical properties are largely restored.

Thus, at least the inventive soldering method explained with reference to the exemplary embodiment is based on a non-isothermal, epitaxial solidification of a solder in a crack or gap or area of a nickel-base alloy, so that the crystal structure, ie. H. Orientation and lattice of the crystal of the substrate, is recorded. Isothermal guided epitaxial solidification processes are state of the art, their disadvantage being that the solidification process for significant gap widths, such as gap widths of 200 microns, is very time consuming, since only the Bohr out of the gap is diffused out, thus the liquidus temperature of the alloy to raise. Since with the onset of solidification elements in the melt accumulate, which lead to a lowering of the liquidus temperature, a tracking of the soldering temperature via a ramp is advantageous in order to accelerate the solidification process, even without completely diffusing the boron out of the gap.

As the embodiment shows in particular, several advantages are made possible according to the invention. When using the exemplary method according to the invention, the solder structures in the repaired areas again have a monocrystalline structure which thus has the associated high mechanical strength, oxidation resistance and remelting temperature.

Because the temperature control is non-isothermal with decreasing temperature, the soldering process is considerably accelerated. As a result, the monocrystalline base material of the turbine components is less thermally stressed and damaged, and the soldering process is also more economical due to its shorter process time.

During epitaxial solidification, it is therefore provided in particular (compare region 14) that the temperature or soldering temperature is non-isothermal and drops, in particular severely monotonically decreasing.

Claims

claims

1. A process for the production or repair of, in particular monocrystalline, turbine or engine components with the steps:

- heating a solder to a temperature which is greater than or equal to the melting temperature of this solder;

- Spend the resulting during this heating melt of the solder in a formed in the turbine or engine component crack or in a formed between two turbine or engine components gap or in a damaged area of a turbine or engine component; and

- Non-isothermal control or regulation of the temperature of the solder or Turbinenbzw. Engine components during an eptitaktischen solidification process of this solder.

2. The method according to claim 1, characterized in that the temperature which is greater than or equal to the melting temperature of this solder and to which the solder is heated in the range of 1100 ° C to 1300 ° C.

3. The method according to any one of the preceding claims, characterized in that the temperature of the solder during an eptitaktischen solidification process of this solder is so non-isothermally controlled that the temperature of the solder during the epti- tactical solidification process falls strictly monotonous.

4. The method according to claim 3, characterized in that the temperature of the solder during an eptitaktischen solidification process of this solder is controlled so non-isothermally that the temperature of the solder during the eptitaktischen solidification process in the form of a ramp or linear strictly monotonically.

5. The method according to any one of the preceding claims, characterized in that the constant or average cooling rate of the solder during the eptitaktischen solidification process of the solder is at least 0.001 K / min, in particular in the range of 100 K / min to 0.001 K / min.

6. The method according to any one of the preceding claims, characterized in that after the heating of a solder to a temperature which is greater than or equal to the melting temperature of this solder and before the eptitaktisches solidification process of the solder for the complete melting or to increase the proportion of the melt Temperature is held for a predetermined period of time.

7. The method according to any one of the preceding claims, characterized in that the solder is a solder alloy to which an additive material is added, wherein the weight ratio of the additive material in the mixture of the solder alloy and the additive material between 0.001 wt .-% and 99 wt .-% , in particular 25% by weight and 50% by weight.

8. component, namely turbine or engine component, which has a solder at least partially, in particular completely, filled gap or crack or damaged area, characterized in that the solder is monocrystalline or at least directed-solidified and contains palladium.

9. Component according to claim 8, characterized in that the solder is formed monocrystalline and in addition to palladium hafnium, yttrium and boron further.

10. Component namely turbine or engine component, in particular component according to claim 8 or claim 9, produced or repaired by a method according to one of claims 1 to 7.