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 treatment of a bi-material metal part and device for implementing this method Technical field

[0001] The present disclosure relates to a method for heat treating a multi-material metal turbine blade, as well as the devices which allow the implementation of this method.

[0002] Such a method can for example be used to form metal turbomachine blades. Such blades are particularly suitable for applications in turbines and high-pressure compressors. Prior art

[0003] With a view to building more efficient turbomachines, the operating temperatures within the turbomachine are increasingly high. This particularly concerns the hot stages of the turbomachine (high-pressure compressor, combustion chamber and high-pressure turbine). In order to meet these increasingly demanding conditions, new multi-material metal 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 the local thermomechanical stresses.

[0004] However, each material of the multi-material blades has different properties. This is particularly problematic for the finishing steps of the blade, for example for the heat treatment steps allowing the dissolution of certain crystalline precipitates and the dissolution of the eutectics formed during solidification. In particular, the temperature ranges of the heat treatments of the different materials making up a multi-material blade can be disjoint.

[0005] In such circumstances, the material having the lowest temperature resistance is limiting for the heat treatments of the other materials. As a result, the microstructure of the materials particularly chosen for their properties over a certain temperature range is degraded. Thus, said desired properties may, in certain cases, not be achieved. The performance of the blade is therefore reduced.

[0006] There is therefore a real need for improvement in this regard. In particular, there is a need for methods for finishing multi-material parts which are free, at least in part, from the aforementioned drawbacks. In this disclosure, the expression "finishing method" designates the end-of-line manufacturing operations ap applied to a part. For example, heat treatment can be considered a finishing method. Statement of the invention

[0007] The present disclosure relates to a heat treatment method for a multi-material metal turbomachine blade, the metal blade comprising a first and a second part each made of different materials, the method comprising: a first heat treatment at a first temperature, the first heat treatment being undergone only 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 method, it becomes possible to heat treat two distinct parts of the same blade, with different properties, with a heat treatment adapted for each of these zones. This is particularly suitable for multi-material metal turbomachine blades. Indeed, this solution makes it possible to circumvent 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 disjoint.

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

[0010] This configuration makes it possible to improve the thermal precision 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 treatments are simultaneous.

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

[0013] In some embodiments, the method comprises a single quench provided after the first and second heat treatments.

[0014] This configuration represents a saving in time, energy and cost, because it makes it possible to avoid an additional heating step which would follow the first heat treatment. Carrying out a single quenching also makes it possible to avoid recrystallization phenomena which can occur when the thermomechanical stresses undergone by the part decrease.

[0015] In some embodiments, during the first heat treatment, the second portion 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 makes it possible to limit 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 cancelled.

[0018] The present disclosure further relates to a furnace suitable for the heat treatment of a multi-material metal turbomachine blade comprising: a hot enclosure configured to be maintained at a first temperature above 1250°C and, to receive a first part of the metal blade, a cold enclosure 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 comprises a thermally insulating separation screen separating the hot enclosure from the cold enclosure, and configured to be traversed by the metal blade.

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

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

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

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

[0023] The above-mentioned characteristics and advantages, as well as others, will appear on reading the detailed description which follows, of exemplary embodiments of the proposed device and method. This detailed description refers to the attached drawings. Brief description of the drawings

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

[0025] In 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 method 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 parts of the metal blade as a function of time, according to a first embodiment of the method of the invention.

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

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

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

[0034] In order to make the disclosure more concrete, an example of a device is described in detail below, with reference to the attached drawings. It is recalled that the invention is not limited to this example.

[0035] The present disclosure concerns 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] [Fig. 1] represents a furnace 100 suitable for implementing the method of the invention. The furnace 100 comprises a hot enclosure 10 and a cold enclosure 12. A separating screen 11 separates the hot enclosure 10 and the cold enclosure 12. The hot enclosure 10 and cold enclosure 12 may, 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 make it possible to maintain a temperature difference between the hot enclosure 10 and the cold enclosure 12 greater than 20°C, for a separation screen 11 having a thickness greater than 1 mm.

[0038] A metal blade comprising a first part 20, a second part 22 and a joining part 21 connecting 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 joining part 21 may correspond to the platform of the blade and the second part 22 may correspond to the root of the blade.

[0039] In the present embodiment, the blade is arranged in the furnace 100 so that the first part 20 of the blade is in the hot enclosure 10 and the second part of the blade 22 is in the cold enclosure 12. The junction part 21 is then in the same plane as the separation 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 enclosure 12 and the second part 22 is arranged in the hot enclosure 10.

[0040] [Fig. 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 an enclosure under controlled pressure or under vacuum. This enclosure can replace the cold enclosure 12, or simply be included within the cold enclosure 12. In order to obtain cooling, the cooling enclosure 30 can be cooled using a gas, typically an inert gas such as argon.

[0041] [Fig. 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 comprises an enclosure configured to receive a liquid in which the second part of the blade 22 can be immersed. This enclosure can be included within the cold enclosure 12. In order to obtain cooling, the cooling enclosure 40 can comprise a liquid, typically a liquid metal such as liquid aluminum.

[0042] [Fig. 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 comprises a cavity 53 (tooling) configured to hold the second part 22. The cavity 53 is cooled, and may for example comprise a water or cryogenic gas cooling circuit. The cavity 53 may replace the cold enclosure 12 or simply be included within the cold enclosure 12.

[0043] In order to implement the method 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 method of the invention.

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

[0046] The solvus and burning temperatures are respectively noted 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.l], the first part 20 of the blade is brought to a temperature T between Tl and Tl', while the second part 22 is maintained at a temperature lower than T2, preferably much lower than T2. ​​For example, the second part 22 may be maintained at 300°C, or even at room temperature.

[0048] The first part 20 is maintained for a certain time at this temperature T, so that the first part 20 is heat treated. For example, the first part 20 may be maintained for at least 10 h at a temperature above 1250°C, preferably above 1310°C. In the present example, the first part 20 is maintained at a constant temperature T. However, the heat treatment temperature T may be variable, and for example be 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 may be cooled by quenching. The quenching may for example be carried out according to a known method, using turbined argon. Optionally, the first part may be cooled to a temperature which may be room temperature.

[0049] Then, 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 maintained 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 maintained 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 maintained at a constant temperature T'. However, the heat treatment temperature T' can be variable, and for example be a succession of plateaus 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 may be cooled by quenching.

[0051] [Fig. 6] represents 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 with the following exception: 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] [Fig. 7] represents 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 method of the invention. The third embodiment is identical to the first embodiment with the following exception: at the end of the heat treatment of the first part 20, the first part is cooled to the temperature T' between T2 and T2'. This temperature T' is the treatment temperature heat treatment of the second part 22. Then, the heat treatment of the second part 22 is carried out and the latter is brought to the temperature T'. During the heat treatment of the second part 22, the first part 20 is also maintained at the temperature T'.

[0053] [Fig. 8] represents 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 T1 and T1', 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 may be maintained at temperatures T and T' respectively for at least 10 h.

[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 exemplary embodiments, it is obvious that modifications and changes may 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 illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

[0059] It is also obvious that all the characteristics described with reference to a method 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 method.

Claims

Claims

1. Heat treatment method for a multi-material metal turbomachine blade, the metal blade comprising a first part (20) and a second part (22) each made of different materials, the method comprising: 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 undergone by the second part (22) of the metal blade.

2. Method according to claim 1, in which the first and second heat treatments are successive.

3. The method of claim 1, wherein the first and second heat treatments are simultaneous.

4. Method according to one of claims 1 to 3, comprising a single quenching provided after the first and second heat treatments.

5. Method according to one of claims 1 to 4, in which during the first heat treatment, the second part (22) of the metal blade is cooled by a fluid.

6. Furnace (100) suitable for the heat treatment of a multi-material metal turbomachine blade comprising: a hot enclosure (10) configured to be maintained at a first temperature above 1250°C and, to receive a first part (20) of the metal blade, a cold enclosure (12) 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 (22), and in which the furnace comprises a thermally insulating separation screen (11) separating the hot enclosure (10) from the cold enclosure (12), and configured to be traversed by the metal blade.

7. Oven according to claim 6, in which the cold enclosure (12) comprises a cooling system (30, 40) by a fluid configured to cool the second part of the blade (22).

8. An oven according to claim 6, wherein the cold enclosure comprises a cooling system (50) and a cavity (53) configured to to welcome and cool the second part of the dawn (22).

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