Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
  • B21J9/00—Forging presses
  • B21J9/02—Special design or construction
  • B21J9/022—Special design or construction multi-stage forging presses
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
  • B21J1/00—Preparing metal stock or similar ancillary operations prior, during or post forging, e.g. heating or cooling
  • B21J1/06—Heating or cooling methods or arrangements specially adapted for performing forging or pressing operations
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
  • B21K3/00—Making engine or like machine parts not covered by sub-groups of B21K1/00; Making propellers or the like
  • B21K3/04—Making engine or like machine parts not covered by sub-groups of B21K1/00; Making propellers or the like blades, e.g. for turbines; Upsetting of blade roots
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C14/00—Alloys based on titanium
• • 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
  • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
  • C22F1/18—High-melting or refractory metals or alloys based thereon
  • C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
  • F01D25/005—Selecting particular materials
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
  • F01D5/12—Blades
  • F01D5/28—Selecting particular materials; Particular measures relating thereto; Measures against erosion or corrosion
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2230/00—Manufacture
  • F05D2230/20—Manufacture essentially without removing material
  • F05D2230/25—Manufacture essentially without removing material by forging
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2230/00—Manufacture
  • F05D2230/40—Heat treatment
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2300/00—Materials; Properties thereof
  • F05D2300/10—Metals, alloys or intermetallic compounds
  • F05D2300/17—Alloys
  • F05D2300/174—Titanium alloys, e.g. TiAl

Definitions

• the present invention relates to a method for producing a component from a TiAl alloy, in which the component is formed by two-stage isothermal forging and is preferably subsequently subjected to a heat treatment.
• the present invention relates to a correspondingly manufactured component.
• TiAl alloys the main components of which are titanium and aluminum, are characterized by the fact that they have sufficient ductility and high strength through the formation of intermetallic phases, such as ⁇ -TiAl, which have a high proportion of covalent binding forces within the metallic bond, especially high temperature resistance.
• intermetallic phases such as ⁇ -TiAl
• they have a low specific weight, so that the use of titanium aluminides or of TiAl alloys for high-temperature applications, for example for turbomachines, in particular gas turbines or aircraft engines, is advantageous.
• the property profile of the TiAl alloys can be further optimized by adding certain alloy components such as niobium and molybdenum.
• alloys with a niobium and molybdenum content are also referred to as so-called TNM alloys.
• alloys are used, for example, to manufacture guide vanes or rotor blades in aircraft engines and are forged into the corresponding component shape.
• isothermal forging with subsequent heat treatment can be used to adjust the structure and the property profile.
• blisks artificial word for blade and disk
• the forging temperature can be raised to 1200 ° C and the main forming can be shifted from the second to the first forging step.
• the recovery mechanisms increase at the expense of the recrystallization mechanisms and part of the dislocation energy that has to be used for structural refinement is lost through recovery.
• Dislocation energy is the energy that is present in the crystal lattice due to small defects; dislocations are inserted atomic planes that end in the middle of the crystal).
• the dislocation density is increased by forging to such an extent that this energy can be used for recrystallization processes.
• the structure is molded in, making it finer and more homogeneous. This is the mechanism why forging is used to achieve higher strengths in materials.
• the microstructure Due to an increasingly stronger recovery of the microstructure, if the increase in the forging temperature and shift of the main forming from the second to the first forging step increases the recovery compared to recrystallization, the microstructure becomes more inhomogeneous and the ductility or the scatter in the total expansion increases. The strength and elongation potential of the material is thus not fully exploited as would be desirable for the application.
• the second degree of deformation can be, for example, no more than 95%, no more than 90%, no more than 85%, no more than 80%, or no more than 75% of the first degree of deformation.
• the TiAl alloy can in particular be a TNM alloy, that is to say an alloy which, in addition to the main components titanium and aluminum, also comprises smaller amounts of niobium and molybdenum (and preferably also boron).
• the method according to the invention can be used particularly advantageously for components made from a TiAl alloy with 42 to 45 at.% Titanium, in particular 42.5 to 54.5 at.% Titanium, 3.5 to 4.5 at.% Niobium , in particular 4.0 to 4.2 at.% niobium, 0.75 to 1.5 at.% molybdenum, in particular 0.9 to 1.2 at.% molybdenum, and 0.05 to 0.15 at% boron , in particular 0.1 to 0.12 at.% boron, balance aluminum and unavoidable impurities.
• the temperature in the first or second forging step is at least 1190 ° C., and in particular at least 1200 ° C., a temperature of about 1200 ° C. being particularly preferred.
• the degree of deformation in the first forging step in the inner region, which the final component geometry comprises is at least 0.55, preferably at least 0.6, and in particular at least 0.65.
• the temperature in the intermediate annealing step is in the range from 1135 ° C. to 1165 ° C., in particular in the range from 1140 ° C. to 1160 ° C.
• a temperature in the range from 1145 ° C. to 1155 ° C. is particularly preferred.
• the hold time at the specified temperature is at least 1 hour, for example at least 1.5 hours or at least 2 hours, and is not longer than 8 hours, for example not longer than 7.5 hours or not longer than 7 hours.
• the expansion potential and the strength of the TiAl material can be increased, especially if more local deformation is introduced in the first isothermal forging step than in second forging step. Furthermore, the yield stresses decrease in the second isothermal forging step, as a result of which the die life can generally be increased and the mold filling can be improved. This reduces the die costs and the strength and the expansion potential of the component are increased and stabilized.
• the intermediate annealing can be carried out, for example, in an oven.
• the intermediate annealing is preferably followed (before the second isothermal forging step) by cooling of the component preliminary stage (preferably by air cooling).
• the component preliminary stage can also be raised directly to the temperature for the second isothermal forging step without cooling.
• At least one heat treatment of the forged component follows the second isothermal forging step (on final contour or near net shape).
• This further heat treatment is preferably carried out at a temperature above the ⁇ -Solvus temperature or below the ⁇ -Solvus temperature, preferably in each case for 20 minutes to 180 minutes.
• the heat treatment is carried out at a temperature in the range from the ⁇ -solvus temperature to 50 ° C., preferably 30 ° C., particularly preferably from 2 ° C. to 25 ° C., in particular from 5 ° C. to 25 ° C.
• the further heat treatment is preferably followed by cooling, preferably at a cooling rate of at least 100 ° C./minute or not more than 500 ° C./minute.
• a further heat treatment can optionally follow the cooling, for example at a temperature of 800 ° C to 950 ° C (stabilization annealing).
• the structure down to local degrees of deformation of approximately 0.7 is molded completely globular.
• this structure can be forged into a shape close to the final contour with little effort (globular structure has less yield stress).
• a subsequent heat treatment as described above can be used to set a homogeneous structure without old colonies remaining from the as-cast state. This more homogeneous structure has a higher strength and thus a higher total elongation than components that were processed without this recrystallization annealing.
• the subsequent heat treatment described above for, for example, 20 minutes to 40 minutes (above the ⁇ -Solvus temperature) or 45 minutes to 180 minutes in a three-phase field (below the ⁇ -Solvus temperature) of the TiAl alloy can be tailored to the requirements almost lamellar microstructures can be adjusted.
• Subsequent cooling at 500 ° C / minute can be used to set very fine creep-resistant slats or slower cooling with up to 100 ° C / minute thicker slats that are more resistant to cellular reactions.
• the phase components can then be adjusted close to the thermal equilibrium at the application temperature by means of a heat treatment for several hours.
• the method according to the invention can be used, for example, to produce components of a turbomachine, in particular components of a gas turbine or an aircraft engine, such as, for example, moving blades, guide blades or turbine blades.
• a turbomachine in particular components of a gas turbine or an aircraft engine, such as, for example, moving blades, guide blades or turbine blades.
• a material for a component produced according to the invention can, for example, have a composition in the range from 42 to 45 at.% Titanium, 3.5 to 4.5 at.% Niobium, 0.75 to 1.5 at.% Molybdenum, and 0.05 up to 0.15 at.% boron, balance aluminum and unavoidable impurities.
• the material of the component is forged by a first isothermal forging step at approx. 1200 ° C with a degree of deformation of approx. 0.6.
• the forged material is then cooled to room temperature by air cooling and then heated for 4 hours at approx. 1150 ° C, followed by a second isothermal forging step at approx. 1200 ° C to an (almost) final contour.
• the component produced in this way can be subjected to a (second) heat treatment at a temperature above the ⁇ -solvus temperature (for example at approximately 1290 ° C.) for, for example, 20 to 40 minutes.
• a (second) heat treatment at a temperature above the ⁇ -solvus temperature (for example at approximately 1290 ° C.) for, for example, 20 to 40 minutes.
• the component is then quickly cooled, for example by cooling with a blower.
• This fan cooling takes place in air or in an oven, the temperature being lowered to below 600 ° C. and then raised to approx. 850 ° C. and kept at this temperature for about 6 hours.
• the ⁇ -TiAl structure set at the temperature of the second heat treatment that is to say at a temperature of approximately 1290 ° C., is largely frozen.
• the component is heated below the ⁇ -Solvus temperature.
• the component is heated at approx. 1235 ° C for about an hour and then cooled (fan cooling). With fan cooling, the temperature is reduced to below 600 ° C and then raised to approx. 850 ° C.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• General Engineering & Computer Science (AREA)
• Forging (AREA)

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• 2018
  • 2018-06-19 DE DE102018209881.6A patent/DE102018209881A1/de not_active Withdrawn
• 2019
  • 2019-06-14 EP EP19180148.9A patent/EP3584334A1/fr not_active Withdrawn
  • 2019-06-18 US US16/444,169 patent/US20190381559A1/en not_active Abandoned

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