EP2402473B1 - Process for producing a single-crystal component made of a nickel-based superalloy - Google Patents

Description

Technical area

The invention relates to the field of materials technology. It relates to a method for producing a single-crystal component consisting of a nickel-base superalloy or directionally solidified component having comparatively large dimensions. With the aid of the method according to the invention, particularly good properties, in particular very good fatigue strength, are achieved with low-cycle stress on the component.

State of the art

Single-crystal components made of nickel-based superalloys have, among other things, a very good material strength at high stress temperatures, but also good corrosion and oxidation resistance as well as good creep resistance. Due to these properties, when using such materials z. As in gas turbines, the inlet temperature of the gas turbine can be increased, whereby the efficiency of the gas turbine plant increases.

Put simply, there are two types of single crystal nickel-base superalloys.

The first type to which the present invention relates may be completely solution annealed so that the entire γ 'phase is in solution. This is the case for example for the known alloy CMSX4 with the following chemical composition (in% by weight): 5.6 Al, 9.0 Co, 6.5 Cr, 0.1 Hf, 0.6 Mo, 3 Re, 6.5 Ta, 1.0 Ti, 6.0 W, Rest Ni or the alloy PWA 1484 with the following chemical composition (in% by weight): 5 Cr, 10 Co, 6 W, 2 Mo, 3 Re, 8.7 Ta, 5.6 Al, 0.1 Hf and the known alloy MC2, which unlike the abovementioned alloys, it is not alloyed with rhenium and has the following chemical composition (in% by weight): 5 Co, 8 Cr, 2 Mo, 8 W, 5 Al, 1.5 Ti, 6 Ta, balance Ni.

A typical standard heat treatment for CMSX4, for example, is the following: solution annealing at 1320 ° C / 2h / shielding gas, fan cooling.

The second type of single crystal nickel base superalloys is not fully heat treatable, i. Here, not the entire portion of the γ'-phase in a solution annealing goes into solution, but only a certain part. This is the case, for example, with the known superalloy CMSX186 having the following chemical composition (in% by weight): 0.07 C, 6 Cr, 9 Co, 0.5 Mo, 8 W, 3 Ta, 3 Re, 5.7 Al, 0.7 Ti, 1.4 Hf, 0.015 B, 0.005 Zr, balance Ni and the alloy CMSX486 with the following chemical composition (in% by weight): 0.07 C, 0.015 B, 5.7 Al, 9.3 Co, 5 Cr, 1.2 Hf, 0.7 Mo, 3 Re, 4.5 Ta, 0.7 Ti, 8.6 W, 0.005 Zr, balance Ni.

The nickel-based superalloys of the second type are usually subjected to a two-stage heat treatment (aging process at lower temperatures), as at higher temperatures, as typically used in the alloys of the first type for solution annealing are already reached, the melting point start temperature, and thus the alloy begins to melt undesirable.

1. 1. Stufe: 1080 °C/4h/Gebläse
2. 2. Stufe: 870 °C/20h/Gebläse.

A typical two-stage heat treatment of the alloy CMSX186 is, for example, the following:

1. 1st stage: 1080 ° C / 4h / blower
2. 2nd stage: 870 ° C / 20h / blower.

The creep resistance of the first type of nickel-base superalloys is usually higher than that of the second type, provided that the alloys belong to the same generation. This is mainly due to the fact that the dissolved γ 'is the main source of recoverable strength.

Nickel-based superalloys for single-crystal components, such as. B. off US 4,643,782 . EP 0 208 645 . US 5,270,123 and US 7,115,175 B2 contain alloying, eg, Re, W, Mo, Co, Cr, as well as γ'-phase-forming elements, for example Al, Ta, and Ti. The content of high-melting alloying elements (W, Mo, Re) in the basic matrix ( austenitic γ phase) increases continuously with the increase of the stress temperature of the alloy. To contain z. B. common nickel-based superalloys for single crystals 6-8% W, up to 6% Re and up to 2% Mo (in% by weight). Furthermore, small amounts of C, B, Hf and Zr are often present. The alloys disclosed in the above references have a high creep strength, a comparatively good LCF (low cycle fatigue fatigue) and HCF (high cycle life fatigue) properties, and a high oxidation resistance.

These known alloys have been developed for aircraft turbines and therefore optimized for short-term and medium-time use, ie the load duration is designed for up to 20,000 hours. In contrast, industrial gas turbine components have to go to one Stress duration of up to 75 000 hours or more can be interpreted.

After a period of use of 300 hours z. For example, the alloy CMSX-4 US 4,643,782 when used experimentally in a gas turbine at a temperature above 1000 ° C a strong coarsening of the y 'phase, which is associated with an increase in the creeping speed of the alloy adversely.

It is well-known in the art to subject such superalloys to a heat treatment after the casting process, in which the γ'-phase, which is nonuniformly precipitated during the casting process, is completely or partially dissolved in the structure in a first solution annealing step. In US 4,328,045 It is also proposed to apply this homogenization and solution annealing step to a directionally solidified nickel-base alloy having a structure consisting mainly of γ'-particles in a γ-matrix and dendrites having a low refracting metal content and interdendritic regions having a high refraction metal -Gehalt has to perform at such a temperature and time that the structure is homogenized with respect to the refractive metal content and then cooled so fast that the re-excretion of the γ'-phase is suppressed and a structure is formed, which with refractive elements is oversaturated. In a second heat treatment step, the γ'-phase is excreted again controlled. In order to achieve optimum properties, this precipitation heat treatment is carried out in such a way that the finest possible uniformly distributed particles of the γ'-phase in the γ-phase (= matrix) are formed.

However, it has been found that when subjected to mechanical stress under long-term high temperature stress (creep) or after plastic deformation of the material at room temperature to which a heat treatment is applied (High-temperature annealing) of the material adjoins, in the structure of such alloys adversely to a directional coarsening of the y 'particles, the so-called rafting (English: rafting) comes. At high γ'-contents (ie at a γ'-volume fraction of at least 50%) this leads to inversion of the microstructure, ie γ 'becomes the continuous phase in which the former γ-matrix is embedded.

Since the γ'-intermetallic phase tends to embrittle the environment, under certain stress conditions, this leads to a massive decrease of the mechanical properties - especially the yield strength - at room temperature (25 ° C) compared to non-specimens previous such creep stress were subjected. This degradation in yield strength is described by the term "degradation" of properties (see Pessah-Simonetti, P. Caron and T. Khan: Effect of long-term prior aging on tensil behavior of high-performance single crystal superalloy, Journal of Physique IV, Colloque C7, Volume 3, November 1993 ).

A similar effect leading to the flocculation of the γ'-phase also results from the solidification of nickel-based superalloys due to dendritic segregation. Especially in superalloys with a high proportion of slowly diffusing elements, such. As rhenium, the segregations of these elements can not be completely eliminated within an acceptable homogenization time. Since the γ'-phase, which precipitates during cooling, has a smaller lattice constant than the γ-matrix and the γ / γ'-lattice offset in the dendrites is larger than in the interdendritic regions, internal stresses are formed during the heat treatment, especially during cooling. This leads to a change in the γ 'microstructure in that the initially cubic form of γ' changes into a stretched form of γ '. This is accompanied by the deterioration of mechanical properties, eg. B. fatigue strength at low load cycles.

Another problem of many known nickel-based superalloys, such as the US 5,435,861 known alloys, is that the castability of large components, eg. B. gas turbine blades with a length of more than 80 mm, leaves something to be desired.

The glazing of a perfect, relatively large directionally solidified single crystal nickel base superalloy component is extremely difficult. Most of these components have errors, e.g. Small angle grain boundaries, "Frecklen", d. H. Defects caused by a chain of rectified grains with a high content of eutectic, equiaxial Streugrenzen, microporosity u. a. These defects weaken the components at high temperatures, so that the desired life or operating temperature of the turbine can not be achieved.

However, because a perfectly cast single crystal component is extremely expensive, the industry tends to allow as many defects as possible without sacrificing service life or operating temperature.

Another possibility is in US 7,115,175 B2 proposed: After casting the single crystal component, the existing microporosities formed during casting are closed and islands of eutectic γ / γ 'phase in the matrix are partially dissolved by a HIP process (hot isostatic pressing, English: hot isostatic pressing ) is applied, then a solution annealing for complete solution of the eutectic γ / γ'-phase and the excretion gleichmäsig distributed large "octet shaped" said γ'-particles is made and then a precipitation heat treatment to second and evenly distributed fine cuboid γ'- To get particles. This is intended to increase the strength of the superalloy.

According to the document US 7,115,175 B2 the process immediately following the casting step is carried out after a two-stage slow heating of the cast object at a final HIP temperature in the range of 1174 ° C (2145 ° F) to 1440 ° C (2625 ° F), wherein the hold time is 3.5 to 4.5 hours and the pressure is in the range of 89.6 MPa (13 ksi) to 113 MPa (16.5 ksi), that is, comparatively low.

The latter also applies to the document Chang, JC et al .: "Development of Microstructure and Mechanical Properties of a Ni-Base Single-Crystal Superalloy by Hot-Isostatic Pressing", Journal of Materials Engineering and Performance, ASM International; Materials Park, OH, Vol. 12, No. 4, 2003, pages 420-425 disclosed HIP process which is carried out following a solution annealing treatment on the superalloy CMSX-4 at a pressure of 100 MPa and at a temperature of 1288 ° C.

With these known methods, therefore, single-crystal components of nickel-base superalloys are produced, which on the one hand are advantageously nonporous and have no eutectic γ / γ 'phases and which, on the other hand, have a γ' morphology with a bimodal γ 'distribution.

In the document US Pat. No. 5,820,700 describes a nickel-base superalloy with a stalk-shaped or equiaxed grain structure that has improved resistance to hydrogen embrittlement and fatigue. By stepwise heating and solution annealing at about 50 ° F above the γ'-solvus temperature, character-like carbides and islands of γ / γ'-eutectic are dissolved. This is followed by a HIP treatment to remove porosities, followed by two heat treatment steps each with air cooling.

A positive effect on the microstructure with regard to the unwanted flocculation described above is not possible with the methods disclosed in these documents.

Presentation of the invention

The aim of the invention is to avoid the mentioned disadvantages of the prior art. The invention is based on the object to provide a suitable method for the production, including heat treatment, of comparatively large single-crystal components or components with directionally solidified structure of known nickel-based superalloys, with which a microstructure can be adjusted that not for raft formation γ'-phase and therefore leads to improved mechanical properties, in particular an improved fatigue life at low load cycles (LCF) of the components.

1. A) Bestimmung des Dendritenarmabstandes (λ) in verschiedenen Bereichen der gegossenen Komponente,
2. B) Identifizierung des langsamsten Diffusionselementes in der Zusammensetzung der jeweiligen Nickel Basis-Superlegierung zur Ermittlung des Diffusionskoeffizienten (D),
3. C) Kalkulation der erforderlichen Zeit (t), die notwendig ist, um die Segregation dieses langsamsten Diffusionselementes auf ≤ 5% zu reduzieren bei einer Lösungsglühtemperatur (T₁), welche einerseits niedriger als die Startschmelztemperatur (T_mi) ist, andererseits aber hoch genug ist, um im notwendigen Wärmebehandlungsfenster zu liegen,
4. D) Lösungsglühen der gegossenen Komponente, umfassend ein Erwärmen der Komponente auf die Lösungsglühtemperatur (T₁), ein Halten bei dieser Temperatur mit der im Schritt C) kalkulierten Zeit (t) und ein Abschrecken von der Lösungsglühtemperatur (T₁) auf Raumtemperatur (RT) mit einer Geschwindigkeit (v1) ≥ 50 °C/min,
5. E) Durchführung der zweistufigen Ausscheidungsbehandlung zur Ausscheidung der γ'-Phase bei jeweils niedrigeren Temperaturen (T₂) und (T₃) im Anschluss an den Schritt D), wobei in der ersten Stufe der Ausscheidungsbehandlung ein HIP-Verfahren mit einem Druck (p) grösser 160 MPa bei der Haltetemperatur (T₂) und einer anschliessenden Abkühlung auf Raumtemperatur (RT) mit einer Abkühlgeschwindigkeit (v2) ≥ 50 °C/min durchgeführt wird, und in der nachfolgenden zweiten Stufe der Ausscheidungsbehandlung eine Wärmebehandlung der Komponente bei einer Haltetemperatur (T₃) und anschliessender Abkühlung auf Raumtemperatur (RT) mit einer Abkühlgeschwindigkeit (v3) von 10 bis 50 °C/min durch geführt wird.

According to the invention, this is achieved in that, in a method according to the preamble of claim 1, the following steps are carried out according to the casting of the component carried out according to the customary state of the art:

1. A) determination of the dendrite arm spacing (λ) in different regions of the cast component,
2. B) Identification of the slowest diffusion element in the composition of the respective nickel-based superalloy for determining the diffusion coefficient (D),
3. C) Calculation of the required time (t) necessary to reduce the segregation of this slowest diffusion element to ≤ 5% at a solution annealing temperature (T ₁ ) which on the one hand is lower than the start melting temperature (T _mi ) but on the other hand high enough is to be in the necessary heat treatment window,
4. D) Solution annealing the cast component comprising heating the component to the solution annealing temperature (T ₁ ), holding at that temperature with the time (t) calculated in step C) and quenching from the solution annealing temperature (T ₁ ) to room temperature (RT ) at a speed (v1) ≥ 50 ° C / min,
5. E) carrying out the two-stage precipitation treatment to separate the γ 'phase at lower temperatures (T ₂ ) and (T ₃ ) following step D), wherein in the first stage of the precipitation treatment a HIP process with a pressure (p ) greater than 160 MPa at the holding temperature (T ₂ ) and subsequent cooling to room temperature (RT) at a cooling rate (v2) ≥ 50 ° C / min, and in the subsequent second stage of the precipitation treatment a heat treatment of the component at a holding temperature (T ₃ ) and subsequent cooling to room temperature (RT) with a cooling rate (v3) of 10 to 50 ° C / min is performed.

With the method according to the invention, it is possible to produce large single-crystal components or components with directionally solidified microstructure of known nickel-base superalloys, which on the one hand are free of pores and on the other hand have a microstructure in which the flocculation of the γ 'phase is avoided. Therefore, the components thus produced have improved mechanical properties, in particular improved low cycle fatigue life (LCF) fatigue strength. The method has the advantage that it is relatively easy to implement.

It is advantageous if the determination of the dendrite arm spacing (λ) according to step A) takes place by metallographic means. This is relatively easy to implement and, for example, can already be carried out prior to the method on the basis of corresponding samples,

Furthermore, it is advantageous if the quenching rate (v1) from solution annealing temperature (T ₁ ) to room temperature is greater than 70 ° C./min, because then extremely fine uniformly distributed γ'-particles are obtained in the γ-matrix.

• Lösungsglühen bei 1290-1310°C/4-6h/Schnellabkühlung mit v1≥50 °C/min
• HIP-Prozess (isostatischer Druck> 160 MPa) mit Erwärmen und Glühen bei 1150 °C/4-8h/Schnellabkühlung mit v2 ≥ 50 °C/min
• Glühen bei 870 °C/16-20h/Abkühlung mit v3 im Bereich von 10-20 °C/min umfasst.

Finally, it is advantageous if the inventive method for producing a component of a nickel-based superalloy having the following chemical composition (in% by weight): 5.6 Al, 9.0 Co, 6.5 Cr, 0.1 Hf, 0.6 Mo, 3 Re , 6.5 Ta, 1.0 Ti, 6.0 W, rest Ni is carried out at the following treatment parameters:

• Solution annealing at 1290-1310 ° C / 4-6h / rapid cooling with v1≥50 ° C / min
• HIP process (isostatic pressure> 160 MPa) with heating and annealing at 1150 ° C / 4-8h / rapid cooling with v2 ≥ 50 ° C / min
• Annealing at 870 ° C / 16-20h / cooling with v3 in the range of 10-20 ° C / min.

Brief description of the drawings

Fig. 1

das Zeit-Temperatur-Diagramm des sich an den Giessprozess anschliessenden Behandlungsverfahren zur Herstellung einer Einkristallkomponente

Fig. 2a-2c

die jeweiligen zu Fig. 1 zugehörenden Gefüge zu Orientierung) und

Fig.3a-3c

die Zeit-Temperatur- bzw. Druck-Temperatur-Diagramme für den HIP-Prozess in drei möglichen Varianten.

In the drawing, an embodiment of the invention is shown. They show schematically:

Fig. 1

the time-temperature diagram of the adjoining the casting process treatment method for producing a single crystal component

Fig. 2a-2c

the respective ones too Fig. 1 belonging structure for orientation) and

3a-3c

the time-temperature or pressure-temperature diagrams for the HIP process in three possible variants.

Ways to carry out the invention

The invention will be explained in more detail with reference to an embodiment and the drawings.

To prepare a large single-crystal component / directionally solidified component, the nickel-base superalloys CMSX4 known from the prior art with the following chemical composition (in% by weight) were used: 5.6 Al, 9.0 Co, 6.5 Cr, 0.1 Hf, 0.6 Mo, 3 Re, 6.5 Ta, 1.0 Ti, 6.0 W, balance Ni.

First, the component, such as a gas turbine bucket, was poured into its mold. Upon solidification of this cast alloy, dendritic segregations arise due to the composition, in particular the comparatively high Re content.

Rhenium is a very slowly diffusing element, so these segregations can not be completely eliminated in the subsequent solution annealing process within an acceptable homogenization time. Since the γ'-phase, which precipitates during cooling, has a smaller lattice constant than the γ-matrix and the γ / γ'-lattice offset in the dendrites is larger than in the interdendritic regions, internal stresses are formed during the heat treatment, especially during cooling. This leads to a degradation in the γ'-microstructure, in that the initially cubic form of γ 'changes into a stretched form of γ'. This is accompanied by the deterioration of mechanical properties, eg. B. fatigue strength at low load cycles.

To avoid this, the dendrite arm spacing λ is therefore first determined in different, for example, the critical regions of the cast component. This can z. B. done by metallographic way, where appropriate, this distance is already determined prior to the process on the basis of corresponding pre-cast samples.

Furthermore, the slowest diffusion element in the composition of the respective nickel base superalloy is identified to determine the diffusion coefficient D. In the present case, this element is rhenium, as already explained above. In the case of the nickel-base superalloy MC2 described in the section "Prior Art" above, this element is Mo.

From the data now known, ie from D and λ, the required time t is calculated at which the component at solution annealing temperature T ₁ , which is lower on the one hand than the starting melt temperature T _mi , and on the other hand high enough to in the necessary heat treatment window must be held so that the microsegregation of this slowest diffusion element is reduced to ≤ 5%.

• mit λ = Dendritenarmabstand
• D = Diffusionskoeffizient (von Rh in Ni für das vorliegende Beispiel)
• δ = Amplitude der Mikrosegregation (hier: 0.05 für eine
• Restsegregation von 5 %

This calculated time t is in the present embodiment 4-6 h at a solution annealing temperature T ₁ of 1290-1310 ° C. You can find them according to the following formula: $$\mathrm{t}={\mathrm{\lambda }}^{\mathrm{2}}\mathrm{ln\delta }/\mathrm{4}{\mathrm{\pi }}^{\mathrm{2}}\mathrm{D}$$

• with λ = dendrite arm spacing
• D = diffusion coefficient (from Rh to Ni for the present example)
• δ = amplitude of microsegregation (here: 0.05 for a
• Residual segregation of 5%

In Fig. 1 is the time-temperature diagram of the subsequent to the casting process treatment method for producing the single crystal component from the above superalloy shown schematically.

The solution annealing (process step D)) of the cast component in the present embodiment thus comprises heating the component to the above solution annealing temperature T ₁ of 1290-1310 ° C, holding at this temperature with the time t calculated above (4-6 h) and a rapid quenching from the solution annealing temperature T ₁ to room temperature at a rate v1 ≥ 50 ° C / min, in order to obtain very fine uniformly distributed γ 'particles in the γ matrix after quenching (Scheme Fig. 2a ). Preferably, the quenching rate is greater than 70 ° C / min, because then a microstructure is obtained with extremely fine uniformly distributed γ'-particles in the γ-matrix.

According to the invention, after the solution annealing, a two-stage precipitation treatment for precipitating the γ'-phase is carried out at lower temperatures T ₂ and T ₃ in comparison to T ₁ (method step E)), wherein in the first stage of the precipitation treatment a HIP method with one pressure p greater than 160 MPa and a cooling rate v2 ≥ 50 ° C / min is applied. The final temperature of the HIP process in the present embodiment is 1150 ° C, the holding time 4-6 h. The applied final pressure during the HIP process is relatively high, it is greater than the internal stresses caused by the inhomogeneities in the microstructure. On the one hand, this method step advantageously closes any micropores present in the microstructure and, on the other hand, eliminates stresses which are caused by the rapid cooling of the solution annealing temperature T ₁ to room temperature or by any residual inhomogeneities in the microstructure. This prevents directional flocculation of the γ 'phase by the formation of the aforementioned cubic γ' particles in the γ matrix. The microstructure present after the HIP-treatment step consists of fine uniformly distributed cubic γ'-particles in the γ matrix and is schematically in orientation Fig. 2b shown.

The realization of the first stage of method step E) is possible in several variants. Corresponding time-temperature or pressure-temperature diagrams for the HIP process are schematically in the 3 a) to 3 c) shown.

At the first, in Fig. 3a In the variant shown, the temperature and pressure are almost identical as a function of time, ie, during the warm-up phase, both the isostatic pressure p acting on the component and the temperature T increase linearly with time until the temperature T ₂ and the isostatic temperature increase Pressure p> 160 MPa, so the isostatic pressure, are reached. After holding these parameters for a certain period of time, a linear decrease of the values as a function of time takes place again for both parameters.

Compared to Fig. 3a will be at the in Fig. 3b variant shown, however, phase-shifted immediately at the beginning of the first stage of process step E) the isostatic final pressure applied abruptly, and also kept constant during the warm-up phase. All other parameters are analogous to here Fig. 3a ,

Finally, it is also possible in a further variant, the first stage of process step E), ie the HIP process, as in Fig. 3c is shown to perform. The isostatic discharge pressure p is here in turn applied abruptly at the beginning of the warm-up phase, and kept constant over the entire warm-up phase, the holding phase at T ₂ and in addition over the entire cooling phase. Only then, when the component has assumed room temperature, the isostatic pressure load is abruptly removed.

With all three variants, beneficial fin formation in the microstructure is prevented.

Finally, as the last step of the process, a further stage of the precipitation heat treatment of the component is carried out. According to the present exemplary embodiment, the single-crystal component / directionally solidified component is heated to a temperature T ₃ of 870 ° C., held at this temperature T _{3 for} 16-20 h and then cooled to room temperature at a cooling rate v3 of approx. 50 ° C./minute ,

The end structure according to the present invention formed after this last treatment step is schematically for the <001> orientation in FIG Fig. 2c shown.

With the method according to the invention, in particular chemical inhomogeneities between dendritic and interdendritic regions in the microstructure are eliminated, thereby reducing or preventing the tendency of local olfief formation of the γ'-phase (in the present embodiment, the fin of the γ'-phase could be formed in the cooling channels of the gas turbine blade prevented) and thus the properties of the components, in particular the fatigue properties at low load cycles, improved.

Claims (4)

1. Method for producing a single-crystal component comprising a nickel-based superalloy, or a directionally solidified component, wherein the component is first cast in a known manner in a mould forming a structure having a dendrite, and then a solution-annealing process is carried out for homogenization of the cast structure of the component and a two-stage precipitation heat treatment is performed, characterised by the following steps:

   A) determining the dendrite arm spacing (λ) in different areas of the cast component,

   B) identifying the slowest diffusion element in the composition of the respective nickel-based superalloy for determining the diffusion coefficient (D),

   C) calculating the required time (t) necessary to reduce the segregation of this slowest diffusion element to ≤ 5% at a solution annealing temperature (T₁) which is firstly lower than the starting melt temperature (T_mi) and secondly however high enough to lie within the necessary heat treatment window,

   D) solution-annealing the cast component, comprising heating of the component to the solution-annealing temperature (T₁), holding at this temperature (T₁) for the time (t) calculated in step C), and quenching from the temperature (T₁) to room temperature (RT) with a speed (v1) ≥ 50°C/min,

   E) carrying out the two-stage precipitation treatment for separating the γ' phase at respectively lower temperatures (T₂) and (T₃) following step D), wherein the first stage of the precipitation treatment comprises carrying out an HIP process with an isostatic pressure (p) greater than 160 MPa at the holding temperature (T₂) and subsequent cooling from the temperature (T₂) to room temperature (RT) with a cooling rate (v2) ≥ 50°C/min, and the subsequent second stage of the precipitation treatment comprises heat treatment of the component at a holding temperature (T₃) and a subsequent cooling from the temperature (T₃) to room temperature with a cooling rate (v3) of 10-50°C/min.
2. Method according to claim 1, characterised in that the dendrite arm spacing (λ) is determined in step A) using a metallographic process.
3. Method according to claim 1, characterised in that the quenching speed (v1) in step D) is > 70°C/min.
4. Method according to one of claims 1 to 3, characterised in that for a nickel-based superalloy with the following chemical composition (data in w.%): 5.6 Al, 9.0 Co, 6.5 Cr, 0.1 Hf, 0.6 Mo, 3 Re, 6.5 Ta, 1.0 Ti, 6.0 W, remainder Ni, the step of solution annealing is carried out with the following parameters: 1290-1310 °C / 4-6 h / rapid cooling with v1 ≥ 50°C/min, the step of the first stage of the γ'precipitation treatment comprises an HIP process with an isostatic pressure (p) > 160 MPa at a holding temperature (T₂) of 1150°C and a holding time of 4-8 h, and rapid cooling takes place with (v2) ≥ 50°C/min, and the second stage of the γ' precipitation treatment comprises heating and holding at 870°C / 16-20 h / and cooling with a rate (v3) of 10-50°C/min.

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