Heat treatment process for a bi-material metal part and device for implementing this process

Abstract

Heat treatment process for a bi-material metal part and device for implementing this process. Heat treatment process for a multi-material metal turbine blade, the metal blade comprising a first (20) and a second part (22) each made of different materials, the process comprising: a first heat treatment at a first temperature, the first heat treatment being carried out only on the first part of the metal blade, and a second heat treatment at a second temperature lower than the first temperature, the second heat treatment being carried out on the second part of the metal blade. Figure for the abstract: Fig. 1.

Description

Title of the invention: Method for heat treating a bi-material metal part and device for implementing this method technical field

[0001] The present exposition relates to a heat treatment process for a multi-material metallic turbine blade, as well as the devices which enable the implementation of this process.

[0002] Such a process can, for example, be used to form metallic turbine blades. Such blades are particularly suitable for applications in high-pressure turbines and compressors. Previous technique

[0003] In order to build more efficient turbomachines, operating temperatures within the turbomachine are becoming increasingly high. This particularly concerns the hot stages of the turbomachine (high-pressure compressor, combustion chamber, and high-pressure turbine). To meet these increasingly demanding conditions, new multi-material metallic blades have been designed. It is then possible to adapt the blade materials to the more demanding conditions within the turbomachine during its operation, taking into account local thermomechanical stresses.

[0004] However, each material in the multi-material blades exhibits different properties. This is particularly problematic for the blade finishing stages, for example, for the heat treatment stages that allow for the dissolution of certain crystalline precipitates and the dissolution of the eutectics formed during solidification. In particular, the temperature ranges for the heat treatments of the different materials composing a multi-material blade may be disjoint.

[0005] In such circumstances, the material with the lowest temperature resistance limits the heat treatment of the other materials. Consequently, the microstructure of the materials specifically chosen for their properties over a certain temperature range is degraded. Thus, the desired properties may, in some cases, not be achieved. The performance of the blade is therefore reduced.

[0006] There is therefore a real need for improvement in this respect. In particular, there is a need for methods of finishing multi-material parts that are free, at least in part, from the aforementioned drawbacks. In this discussion, the term "finishing method" refers to the end-of-line manufacturing operations applied on a part. For example, heat treatment can be considered a finishing method. Description of the invention

[0007] The present description relates to a heat treatment process for a multi-material metal turbine blade of a turbomachine, the metal blade comprising a first and a second part each made of different materials, the process comprising: a first heat treatment at a first temperature, the first heat treatment being only undergone by the first part of the metal blade, and a second heat treatment at a second temperature lower than the first temperature, the second heat treatment being undergone by the second part of the metal blade.

[0008] According to such a process, it becomes possible to heat-treat two distinct parts of the same blade, with different properties, using a heat treatment adapted to each of these areas. This is particularly suitable for multi-material metal turbine blades. Indeed, this solution makes it possible to overcome the difficulties encountered until now in the finishing of bi-material blades, in which the temperature ranges of the heat treatments required for the blade materials are disparate.

[0009] In some embodiments, the first and second heat treatments are successive.

[0010] This configuration improves the thermal accuracy of the heat treatment. In particular, this configuration is advantageous for limiting the effects of thermal diffusion within the metal blade.

[0011] In some embodiments, the first and second heat treatment are simultaneous.

[0012] This configuration represents a time saving, because the blade materials undergo their respective heat treatments simultaneously. The overall heat treatment time of the blade is therefore shorter.

[0013] In some embodiments, the process includes a single quenching step planned after the first and second heat treatment.

[0014] This configuration represents a saving of time, energy, and cost, as it eliminates the need for an additional heating step following the initial heat treatment. Furthermore, performing a single quenching operation prevents recrystallization phenomena that can occur when the thermomechanical stresses experienced by the part decrease.

[0015] In some embodiments, during the first heat treatment, the second part of the metal blade is cooled by a fluid.

[0016] The fluid can be a gas or a liquid.

[0017] In this configuration, a thermal gradient is established between the first part and the second part. This thermal gradient limits the temperature of the second part. In this way, the impact of the heat treatment of the first part on the second part is greatly reduced, or even eliminated.

[0018] The present description also relates to a furnace adapted for the heat treatment of a multi-material metal turbine blade comprising: a hot chamber configured to be maintained at a first temperature above 1250°C and, to receive a first part of the metal blade, a cold chamber configured to be maintained at a second temperature above 1100°C and below the first temperature, and to receive a second part of the metal blade, and in which the furnace includes a thermally insulating separating screen separating the hot chamber from the cold chamber, and configured to be traversed by the metal blade.

[0019] Such a furnace makes it easy to implement the process of the present invention. In particular, such a furnace is especially suitable for carrying out simultaneous heat treatments for metal blades comprising several materials.

[0020] In some embodiments, the cold enclosure includes a fluid cooling system configured to cool the second part of the blade.

[0021] In some embodiments, the cold housing includes a cooling system and a footprint configured to accommodate and cool the second part of the blade.

[0022] In this configuration, the impact of temperature within the metal blade is reduced.

[0023] The aforementioned features and advantages, as well as others, will become apparent from the following detailed description, examples of embodiments of the proposed device and method. This detailed description refers to the accompanying drawings. Brief description of the drawings

[0024] The attached drawings are schematic and are intended primarily to illustrate the principles of the exposition.

[0025] On these drawings, from one figure to another, identical elements (or parts of elements) are identified by the same reference signs.

[0026] [Fig. 1] Fig. 1 schematically represents an oven for implementing the process according to a first embodiment.

[0027] [Fig.2] Fig.2 schematically represents an oven according to a first variant.

[0028] [Fig.3] Fig.3 schematically represents an oven according to a second variant.

[0029] [Fig.4] Fig.4 schematically represents an oven according to a third variant.

[0030] [Fig.5] Fig.5 represents the evolution of the temperature perceived by the first and second part of the metal blade as a function of time, according to a first embodiment of the process of the invention.

[0031] [Fig.6] Fig.6 represents the evolution of the temperature perceived by the first and second part of the metal blade as a function of time, according to a second embodiment of the process of the invention.

[0032] [Fig.7] Fig.7 represents the evolution of the temperature perceived by the first and second part of the metal blade as a function of time, according to a third embodiment of the process of the invention.

[0033] [Fig.8] Fig.8 represents the evolution of the temperature perceived by the first and second part of the metal blade as a function of time, according to a fourth embodiment of the process of the invention. Description of the implementation methods

[0034] To make the explanation more concrete, an example of a device is described in detail below, with reference to the accompanying drawings. It should be noted that the invention is not limited to this example.

[0035] The present exposition focuses on the finishing of a metal blade. The first part 20 and the second part 22 are made of two different materials. For example, the first part 20 may be the commercial alloy CMSX-4® while the second part may be the commercial alloy AMI®s.

[0036] Figure 1 represents a furnace 100 suitable for implementing the process of the invention. The furnace 100 comprises a hot chamber 10 and a cold chamber 12. A separating screen 11 separates the hot chamber 10 and the cold chamber 12. The hot chamber 10 and the cold chamber 12 can, for example, be suitable for heating a material by convection or by induction.

[0037] The separation screen 11 is thermally insulating. For example, the separation screen 11 can maintain a temperature difference between the hot enclosure 10 and the cold enclosure 12 greater than 20°C, for a separation screen 11 with a thickness greater than 1 mm.

[0038] A metal blade comprising a first part 20, a second part 22 and a connecting part 21 linking the first part 20 and the second part 22 is arranged in the furnace 100. For example, the first part 20 may correspond to the blade of the blade, the connecting part 21 may correspond to the platform of the blade and the second part 22 may correspond to the foot of the blade.

[0039] In the present embodiment, the blade is arranged in the furnace 100 such that the first part 20 of the blade is in the hot chamber 10 and the second part of the blade 22 is in the cold chamber 12. The joining part 21 is then in the same plane as the separating screen 11 of the furnace 100. It should be noted that the reverse configuration is also feasible, so that the first part 20 is arranged in the cold chamber 12 and the second part 22 is arranged in the hot chamber 10.

[0040] Figure 2 represents a first variant of the furnace 100, comprising a cooling system 30. In the case of the first variant, the cooling system 30 comprises a chamber under controlled pressure or vacuum. This chamber can replace the cold chamber 12, or simply be contained within the cold chamber 12. In order to achieve cooling, the cooling chamber 30 can be cooled using a gas, typically an inert gas such as argon.

[0041] Figure 3 represents a second variant of the furnace 100, comprising a cooling system 40. In the case of the second variant, the cooling system 40 includes a chamber configured to receive a liquid into which the second part of the blade 22 can be immersed. This chamber can be contained within the cold chamber 12. In order to achieve cooling, the cooling chamber 40 can contain a liquid, typically a liquid metal such as liquid aluminum.

[0042] Figure 4 shows a third variant of the furnace 100, comprising a cooling system 50. In the case of the third variant, the cooling system 50 includes a cavity 53 (tooling) configured to hold the second part 22. The cavity 53 is cooled and may, for example, include a water or cryogenic gas cooling circuit. The cavity 53 may replace the cold chamber 12 or simply be contained within the cold chamber 12.

[0043] In order to implement the process of the present invention, the metal blade is placed in the furnace 100. We are now interested in the control of the furnace 100 which results in the heat treatment of the metal blade.

[0044] Fig. 5 represents the evolution of the temperature perceived by the first part 20 and the second part 22 as a function of time, for a heat treatment according to a first embodiment of the process of the invention.

[0045] Every material has a solvus temperature and a burn temperature. To obtain satisfactory heat treatment for a material, it must be heated above its solvus temperature but below its burn temperature. Indeed, above the burn temperature, the material degrades.

[0046] The solvus and burn temperatures are respectively noted as Tl and Tl' for the first material and T2 and T2' for the second material.

[0047] In the first embodiment, and as shown in [Fig. 1], the first part 20 of the blade is heated to a temperature T between T1 and T1', while the second part 22 is maintained at a lower temperature than T2, preferably much lower than T2. ​​For example, the second part 22 can be maintained at 300°C, or even at room temperature.

[0048] The first part 20 is held for a certain time at this temperature T, so that the first part 20 is heat-treated. For example, the first part 20 can be held for at least 100 at a temperature above 1250°C, preferably above 1310°C. In the present example, the first part 20 is held at a constant temperature T. However, the heat-treatment temperature T can be variable, and for example, consist of a succession of plateaus at a plurality of temperatures. Once the heat treatment of the first part 20 is complete, the first part 20 is cooled. For example, the first part 20 can be cooled by quenching. Quenching can, for example, be carried out using a known method, with the aid of turbinated argon. Optionally, the first part can be cooled to a temperature that can be ambient temperature.

[0049] Next, the first part 20 and the second part 22 are brought to a temperature T' between T2 and T2'. The first part 20 and the second part 22 are held for a certain time at this temperature T', so that the second part 22 is heat-treated. For example, the second part 22 can be held for at least 1 hour at a temperature T' above 1100°C, preferably above 1290°C. In the present example, the second part 22 is held at a constant temperature T'. However, the heat-treatment temperature T' can be variable, and for example, consist of a succession of stages at a plurality of different temperatures.

[0050] Once the heat treatment of the second part 22 is complete, the first part 20, the joining part 21, and the second part 22 are cooled. For example, the first part 20, the joining part 21, and the second part 22 can be cooled by quenching.

[0051] Figure 6 shows the evolution of the temperature perceived by the first part 20 and the second part 22 of the metal blade as a function of time, according to a second embodiment of the method of the invention. The second embodiment is identical to the first embodiment except that during the heat treatment of the second part 22, the first part is maintained at a temperature lower than T2, preferably much lower than T2. ​​For example, the first part can be maintained at 300°C, or even at room temperature.

[0052] Figure 7 shows the evolution of the temperature perceived by the first part 20 and the second part 22 of the metal blade as a function of time, according to a third embodiment of the process of the invention. The third embodiment is identical to the first embodiment except for the following: at the end of the heat treatment of the first part 20, the first part is cooled to the temperature T' is between T2 and T2'. This temperature T' is the heat treatment temperature of the second part 22. The second part 22 then undergoes heat treatment and is brought to temperature T'. During the heat treatment of the second part 22, the first part 20 is also maintained at temperature T'.

[0053] Figure 8 shows the evolution of the temperature perceived by the first part 20 and the second part 22 of the metal blade as a function of time, according to a fourth embodiment of the method of the invention. In the fourth embodiment of the invention, the heat treatment of the first part 20 and the heat treatment of the second part 22 are carried out simultaneously.

[0054] Thus, in the fourth embodiment, the first part 20 of the blade is brought to a temperature T between Tl and Tl', and the second part 22 is simultaneously brought to a temperature T' between T2 and T2'.

[0055] The first part 20 and the second part 22 are maintained at temperatures T and T' respectively until they are heat-treated. For example, the first part 20 and the second part 22 can be maintained at temperatures T and T' respectively for at least 100.

[0056] The first part 20 and the second part 22 are then cooled, for example by quenching.

[0057] Optionally, the first part 20 and the second part 22 can be brought to the respective temperatures T and T' separately and / or cooled separately, so that the holding times at temperatures T and T' are different.

[0058] Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

[0059] It is also evident that all the characteristics described with reference to a process are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a process.

Claims

Demands

1. A heat treatment method for a multi-material metal turbine blade, the metal blade comprising a first part (20) and a second part (22) each made of different materials, the method comprising: positioning the metal blade in a furnace having a hot chamber (10), a cold chamber (12) and a separating screen (11), said separating screen (11) separating the hot chamber (10) from the cold chamber (12), the first part (20) of the metal blade being arranged in one of the hot chamber (10) and the cold chamber (12), the second part (22) being arranged in the other of the hot chamber (10) and the cold chamber (12), a first heat treatment at a first temperature, the first heat treatment being undergone only by the first part (20) of the metal blade, and a second heat treatment at a second temperature lower than the first temperature,the second heat treatment being carried out on the second part (22) of the metal blade, the first and second heat treatments being simultaneous.

2. A method according to claim 1, comprising a single quenching provided after the first and second heat treatment.

3. A method according to claim 1 or 2, wherein during the first heat treatment, the second part (22) of the metal blade is cooled by a fluid.

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