Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/34—Methods of heating
  • C21D1/42—Induction heating
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/02—Induction heating
  • H05B6/36—Coil arrangements
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D2221/00—Treating localised areas of an article
  • C21D2221/10—Differential treatment of inner with respect to outer regions, e.g. core and periphery, respectively
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/25—Process efficiency

Definitions

• the invention relates to the generation of structural gradient microstructure in mechanical parts, and more particularly in axisymmetric parts hollowed in their center.
• Environmental standards such as the ACARE 2020 standard, as well as cost-of-ownership reduction requirements, ie operation and maintenance costs imposed by aircraft manufacturers, require engine manufacturers to develop turbojets with performance always better, especially with a sharp reduction in specific consumption.
• One way to push the limits of materials is to adapt the microstructure of a room to the local mechanical stress of this room. Indeed, in a room, the mechanical stresses can be of different nature depending on the area. Therefore the optimal microstructure can vary within the room depending on the areas considered. In other words, it seeks to achieve on the same part, a dual or gradient microstructure.
• a turbine disk which is one of the most thermo-mechanically stressed parts in the turbojet
• the performance of a material lies in its ability to achieve, for an optimized homogeneous microstructure, the best compromise between the different properties. mechanical requirements, often contradictory.
• the use of a dual or gradient microstructure for the realization of a turbine disk would avoid this compromise.
• a fine-grained disk-bored structure would be needed for its medium-temperature tensile and fatigue characteristics and a coarse grain structure in the rim of the same disk for better creep and cracking properties. temperature.
• fine-grained structure is meant a structure for which the grains are blocked by the Y or ⁇ phase, and by coarse-grained structure a structure for which the grains are no longer blocked by these phases.
• the size of the grains in a structure is given according to the ASTM standard in which 1 ASTM corresponds to a grain of 225 ⁇ m, that is to say a coarse grain, and 10 ASTM correspond to a grain of 10 ⁇ m. that is, to a fine grain.
• the size of a grain corresponds to that of a fine grain if it is greater than 9 ASTM.
• the grain size from which one considers to be in the presence of a large grain is variable. In general, it must be greater than 7 ASTM. This is particularly the case for alloys developed by powder metallurgy (N18, N19). For conventional AD730, R65, and U720 alloys, a grain will be considered large if its size is less than 4 ASTM, and for Inco718, depending on the temperature reached, a grain will be considered large if its size is between 3 and 6 ASTM.
• One known means for achieving structural gradients on a disk type part is a heat treatment itself with a gradient.
• the objective of this temperature gradient treatment is to carry out a dissolution treatment at a temperature stepped in the room in such a way that:
• the temperature is greater than the dissolution temperature of the phase blocking the grain boundaries, also called the solvus temperature, and
• the temperature is below this solvus temperature.
• the grain boundary corresponds to the interface between two crystals of the same nature in a polycrystalline structure.
• the phases in question are the Y or ⁇ phases.
• the solvus temperature of the phases Y or ⁇ the grains will enlarge to form a structure favorable to the properties of creep and cracking, whereas in the zones whose temperature will remain lower than the temperature of the solvus during the treatment, the structure will retain the grain size resulting from forging which is generally relatively fine and favorable to the properties of traction and fatigue.
• the entire disk is carried in an oven at a temperature sufficient to make the grain grow.
• Areas for which a fine-grained structure is desired ie areas that must be maintained below the solvus temperature, are cooled by local air cooling systems, as described in US 5527020 and US 5312497, or by isolation, as described in US 6660110. These systems have the disadvantage of being heavy to implement and not flexible depending on the geometry of the room.
• a second strategy is to apply a local induction heating on the peripheral area of the room. As described in US 4785147 and US 3741821, this strategy is conventionally used to reinforce locally by treating gear teeth. Applied to a turbojet disk, this consists of heating the outside of the room locally by induction. A high frequency current is applied on an induction coil surrounding the part so that a high frequency electromagnetic field comes to be coupled to the part to heat it. A heat gradient is then established in the room between the induction heated exterior and the open air center.
• this local induction heating mode leads to very fast surface cooling when the heating is stopped. But for some alloys, sensitive to quenching tap, this can lead to cracking of the material.
• the aim of the invention is to overcome the drawbacks mentioned above by proposing a structure gradient microstructure generation device on an axisymmetric mechanical part hollowed out at its center making it possible to adjust the temperatures in the zones of the mechanical part to be treated by reducing thermomechanical stresses.
• a device for generating a structural gradient microstructure on an axisymmetric mechanical part hollowed out at its center and initially having a uniform fine grain structure comprising a first heating means defining a first chamber for receiving the mechanical part and able to heat the outer periphery of said mechanical part at a first temperature above the solvus temperature.
• the device comprises a second heating means defining a second enclosure disposed inside the first enclosure and adapted to heat the inner periphery of said mechanical part at a second temperature below the temperature of solvus, the space between the first enclosure and the second enclosure defining a housing adapted to accommodate the axisymmetric mechanical part hollowed in its center.
• a second heating means mounted opposite the inner periphery of the annular piece to be treated makes it possible, in cooperation with the first heating means mounted on the outer periphery of the annular mechanical part to be treated, to simultaneously heat the both outside and inside the disc through two separate heating means.
• This dual heating configuration can even be used to reverse heat flow when necessary.
• This scheme is particularly suitable for turbojet engines which have a hollow bore for the passage of the central shaft of the engine and which can be placed in the housing provided between the two heating devices.
• This device ensures throughout the treatment and especially during temperature maintenance, a controlled temperature difference between the disk areas. It allows to adjust the temperatures in the different zones of the room and especially to establish a state of equilibrium during the maintenance in temperature. It also makes it possible to control the positioning of the transition zone between the coarse grain and fine grain structures.
• These controls are mainly based on the temperature setpoints given to the two heating means and depending on the geometry of the mechanical part processed.
• the first heating means disposed outside the mechanical part to be treated can be used to locally heat the outside of the disk to a temperature sufficient to make the grain grow, that is to say at a higher temperature at the solvus temperature, and the second heating means disposed therein can locally heat the interior of the disc to a temperature below the grain magnification temperature of the material.
• the regulation of the two heating means will make it possible to establish a thermal gradient in the room which will lead to a microstructure gradient.
• the device of the invention defined above comprising the two heating means makes it possible to limit the thermomechanical stresses as soon as the start of treatment by adjusting the temperature difference between the bore and the rim.
• a first example of parts to be treated may correspond to turbine disks having an outside diameter of about 500 mm and an inner diameter of about 100 to 150 mm made of a conventionally-developed nickel alloy of Inco718 type, or of type AD730 or Rene65 or prepared by powder metallurgy, type N18 or N19.
• a second example of a workpiece may correspond to labyrinth rings of outer diameter of about 800 mm and inner diameter of about 650 mm made of inco718-type nickel base alloy, or of Waspaloy, AD730 or Rene65 type.
• this comprises a control unit configured to deliver a first temperature setpoint to the first heating means and a second setpoint temperature to the second heating means, the control unit comprising a synchronization module able to coordinate the emission of the first and second temperature setpoints so that the first heating means and the second heating means operate simultaneously during a heating phase and / or a cooling phase of structure gradient microstructure generation.
• the simultaneous control of the two heating means makes it possible to constantly control the thermomechanical stresses imposed on the mechanical part to be treated, and in particular to prevent too much temperature being applied to an area of the part to be treated.
• control unit comprises a module for regulating the heating temperature difference between the first heating means and the second heating means capable of determining the value of the first temperature setpoint and the value of the second temperature setpoint as a function of the desired positioning of an intermediate zone between a coarse grain structure and a fine grain structure of the mechanical part.
• Control of the device can thus be achieved not by defining temperature setpoints, but simply by defining a precise location of an intermediate zone separating the coarse-grained zone from the fine-grained zone, the control unit comprising a cartography for determining from this intermediate zone location instruction the temperature setpoints to be transmitted to the first and second heating means.
• the first and the second heating means respectively comprise a first inductor and a second inductor.
• first and second inductor as first and second heating means provides the possibility of operation in the air of the device unlike the main devices of the state of the art.
• inductors as heating means provides a simplified control from the supply current, the temperature setpoints determined by the control unit being converted into inductors supply current setpoint by the control unit before their transmission to the first and second inductors.
• control unit comprises a regulation module for the frequency of the currents flowing respectively in the first inductor and in the second inductor.
• the regulation of the frequency of the currents flowing in the first and second inductors makes it possible to control the transition zone in the mechanical part.
• the induced frequencies used are between 5 and 30 kHz, in order to be in an inductive loop with a high skin thickness.
• thick skin of an inductive loopback is meant an inductive looping penetrating heart of the room to be heated for melting or space heating.
• an inductive looping with a small thickness of skin corresponds to an inductive looping directed towards the surface of the part and recommended to repel, levitate, form, while heating.
• This frequency regime has the effect of heating the room preferentially in depth rather than on the surface.
• the adaptive frequency balance is built to operate between 5 and 30 kHz, but the frequency is a result of the combination of the inductor adapter box, relative to the diameter and the number of turns, and the geometry of the piece. Two pieces of different geometry placed in the same set composed of the adapter box and the inductor will provide a different frequency balance but in the range of 5 to 30 kHz.
• the subject of the invention is also a method of generating a structure gradient microstructure on an axisymmetric mechanical part hollowed out at its center, comprising a heat treatment of a mechanical part initially having a uniform fine grain structure, the heat treatment having a first heating of the outer periphery of the mechanical part at a first temperature higher than the solvus temperature.
• the heat treatment further comprises a second heating of the inner periphery the mechanical part at a second temperature lower than the solvus temperature.
• a first aspect of the method for generating a structure gradient microstructure comprises an emission of a first heating temperature setpoint of the outer periphery of the mechanical part and an emission of a second temperature setpoint. heating the inner periphery of the mechanical part, said two emissions being synchronized so that the first heating and the second heating operate simultaneously during a heating phase and / or a cooling phase of the microstructure generation to structure gradient.
• the method of generating a structure gradient microstructure comprises a regulation of the heating temperature difference between the first heating and the second heating, the values of the first temperature setpoint and the second temperature setpoint being determined according to the desired positioning of the intermediate zone between the coarse grain structure and the fine-grained structure of the piece.
• the first heating and the second heating are respectively performed by the circulation of a first current in a first inductor and the circulation of a second current in a second inductor separate from the first inductor.
• a fourth aspect of the method of generating a structure gradient microstructure comprises a regulation of the frequency of the first and second currents flowing respectively in the first inductor and in the second inductor.
• Another object of the invention is a turbine disk comprising at least one structural gradient microstructure portion generated by the method defined above.
• the invention also relates to a turbomachine comprising at least one turbine disk as defined above.
• the invention also has another object, an aircraft comprising at least one turbomachine as defined above.
• an aircraft comprising at least one turbomachine as defined above.
• FIG. 1 shows a perspective view of a device for generating a structure gradient microstructure according to the invention
• Figure 2 shows schematically a sectional view of the device of Figure 1;
• FIG. 3 presents a graphical representation of the thermal topography inside a mechanical part placed in the device of FIG. 1.
• Figures 1 and 2 respectively show a perspective view and a sectional view of a device for generating a structural gradient microstructure according to the invention.
• annular mechanical part P for example a turbine disc, placed in a device 1 for generating a structure gradient microstructure. Before any heat treatment by the device 1, the mechanical part P has a uniform fine-grained structure.
• the device 1 comprises a first heating inductor 2 and a second heating inductor 3.
• the mechanical part P and the first and second heating inductors 2 and 3 are shown in Figure 1 only in part.
• the first heating inductor 2 is formed of four turns 21, 22, 23 and 24 of greater radius than the outer radius of the annular mechanical part P.
• the first heating inductor 2 is configured to heat the outer periphery E of the mechanical part P at a first temperature Ti greater than the solvus temperature, that is to say greater than the dissolution temperature of the phase blocking the joints. grains.
• the second heating inductor 3 is formed of two turns 31 and 32 of radius less than the inner radius of the annular mechanical part P.
• the second heating inductor 3 is configured to heat the inner periphery I of said mechanical part P at a second temperature T 2 lower than the solvus temperature.
• the first heating inductor 2 forms a first closed enclosure inside which is disposed a second enclosure formed by the second heating inductor 3.
• the two enclosures formed by the two heating inductors 2 and 3 thus define an annular housing L extending between the two speakers.
• the housing L is shaped to receive the annular mechanical part P.
• the device 1 can operate in air and does not require the establishment of a vacuum structure in which the mechanical part P must be placed.
• the device 1 further comprises a control unit 4 to which the first heating inductor 2 and the second heating inductor 3 are electrically connected.
• the control unit 4 comprises input means, not shown, for entering, as the case, two separate temperature setpoints for the two heating inductors 3 and 4 or the location of an intermediate zone.
• the location of the intermediate zone makes it possible to define the location of the transition zone between the fine grains and the coarse grains in the mechanical part P after the treatment by the device 1.
• the control unit 4 is configured to deliver, from the information entered using the input means, a first temperature setpoint to the first heating inductor 2 and a second temperature setpoint to the second heating inductor 3.
• first temperature Ti for example for a mechanical part P nickel base alloy of the order of 1040 to 1060 ° C for an Inco type alloy 718, or of the order of 1120 to 1140 ° C for a type alloy AD730 or Rene65 type, or of the order of 1160 to 1180 ° C for an alloy made with a metallurgy powders N 19, and that the internal part I of the mechanical part P is at the second temperature T 2 , for example for a mechanical part P nickel-based alloy of the order of 980 to 1000 ° C for an alloy of Inco type 718, or the order of 1060 to 1080 ° C for an alloy type AD730 or Rene65 type, or of the order of 1110 to 1130 ° C for an alloy made with a powder metallurgy N19 type.
• the control unit 4 comprises a control module 5 of the heating temperature difference between the first heating inductor and the second heating inductor configured to determine the value of the first temperature setpoint and the second temperature setpoint. a function of the desired positioning of an intermediate zone between a coarse grain structure and a fine grain structure of the mechanical part.
• the control unit 4 further comprises a synchronization module 6 configured to coordinate the transmission of the first and second temperature setpoints determined by the control unit 4 so that the first heating inductor 2 and the second heating inductor 3 operate simultaneously during a heating phase and / or a cooling phase of the structure gradient microstructure generation.
• the coordination of the two heating inductors 2 and 3 by means of the synchronization means 6 of the control unit 4 makes it possible simultaneously to heat both the outside and the inside of the disc while at the same time controlling the temperatures
• the temperatures applied to the mechanical part P by the two inductors 2 and 3 can remain at the same time. lower than the maximum temperatures allowed by the mechanical part P and thus avoid any risk of burns of the part P since the internal zone of the mechanical part also receives heat energy from the second heating inductor 3.
• the heating inductors 2 and 3 maintain a controlled temperature difference between the zones of the mechanical part P.
• the control unit 4 controls the temperature drop by adjusting the temperature setpoints applied to the first and second inductors 2 and 3 so as to constantly maintain the same temperature difference.
• the method of treatment by the device 1 can last between
• the device 1 comprises two insulators 7 and 8 each placed respectively on the lower face 9 and on the upper face 10 of the annular mechanical part P.
• the first insulator 7 is placed on the lower face 9 of the mechanical part P so as to cover the entire lower surface 9 of the mechanical part P extending from the outer periphery E to the inner periphery I and the second inductor 3.
• the second insulator 8 is placed on the upper face 10 of the mechanical part P so as to cover the entire upper surface 10 of the mechanical part P extending from the inner periphery I to the outer periphery E as well as the second inductor 3.
• insulators are particularly useful for mechanical parts P of very large dimensions for which the distance between the first inductor 2 and the second inductor 3 is very important to the point that the heat losses along the part can alter the heating efficiency by the two inductors 2 and 3.
• the invention thus provides a structure-gradient microstructure generation device on an axisymmetric mechanical part hollowed out at its center making it possible to adjust the temperatures in the zones of the mechanical part to be treated while reducing the thermomechanical stresses experienced by the part.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electromagnetism (AREA)
• Powder Metallurgy (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Heat Treatment Of Articles (AREA)
• General Induction Heating (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

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• 2015
  • 2015-11-06 FR FR1560653A patent/FR3043410B1/fr active Active
• 2016
  • 2016-11-04 CA CA3004391A patent/CA3004391C/fr active Active
  • 2016-11-04 US US15/773,917 patent/US10837069B2/en active Active
  • 2016-11-04 RU RU2018120600A patent/RU2719236C2/ru active
  • 2016-11-04 CN CN201680074665.4A patent/CN108431239B/zh active Active
  • 2016-11-04 EP EP16809130.4A patent/EP3371334B1/fr active Active
  • 2016-11-04 WO PCT/FR2016/052859 patent/WO2017077248A1/fr not_active Ceased
  • 2016-11-04 JP JP2018522979A patent/JP7166918B2/ja active Active
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