EP2386663B1 - Method for producing a component and component from a gamma-titanium-aluminium base alloy - Google Patents

Description

The invention relates to a method for producing a component from a titanium-aluminum base alloy.

Furthermore, the invention relates to a component made of a titanium-aluminum base alloy, produced with dimensions close to the final dimensions.

Titanium-aluminum base alloys generally have high strength, low density, and good corrosion resistance, and are preferably used as components in gas turbines and aircraft engines.

Alloys having a composition of: aluminum 40 at.% To 50 at.%, Niobium 3 at.% To 10 at.%, Molybdenum to 4 at.%, And optionally the elements manganese, are suitable for the above fields of application. Boron, silicon, carbon, oxygen and nitrogen in low concentrations as well as titanium as the remainder of interest.

These alloys preferably solidify completely over the β-mixed crystal and undergo a series of phase transformations upon subsequent cooling. A schematic diagram ( Fig. 1 ) shows microstructures as a function of the temperature and the aluminum concentration with temperature range information used by the person skilled in the art.

Prepared the components can be by casting an ingot or powder by H eiß- I sostatisches- P ests (HIPing) of alloyed metal powder as well as by casting an ingot and optionally HIPing thereof followed by extrusion molding and each with a subsequent forging of the ingot or intermediate to a Component, which is subsequently subjected to heat treatments.

Titanium-aluminum materials have only a narrow temperature window for a hot forming, although through the alloying elements niobium and molybdenum can be extended, nevertheless, there are limitations with respect to the deformation or forging of the parts. It is known, by slow, isothermal deformation, familiar to those skilled in the art as Isothermschmieden to produce a component at least partially by chipless shaping, but this is associated with great expense.

At most, a component produced by the above technologies will usually not have a homogeneous microstructure because, on the one hand, a low and unequal recrystallization potential of the slowly isothermally deformed material is given, and / or, on the other hand, a time-consuming diffusion of the atoms of the elements niobium and / or molybdenum are important for a deformability of a material, align themselves with the forming structure and thus can adversely affect the structure.

Although a homogenization of the structure formation and thus an achievement of isotropic, mechanical properties of the material by time-consuming annealing treatments are in principle possible, however, requires a lot of effort.

For industrial practice, components made of a titanium-aluminum base alloy are required, which have direction-independent, homogeneous, mechanical properties, the ductility, strength and creep resistance of the material are balanced even at high operating temperatures at a high level.

From the prior art, the following methods or components are known:

• SCHMOELZER T ET AL: "Phase fractions, transition and ordering temperatures in TiAl-Nb-Mo alloys: An in- and ex-situ study ";
• CLEMENS H ET AL: "In and ex situ investigations of the beta-phase in a Nb and Mo containing gamma-TiAl based alloy ";
• HABEL U ET AL: "PROCESSING, MICROSTRUCTURE AND TENSILE PROPERTIES OF .GAMMA.-TIAL PM ALLOY 395MM ";
• D. ZHANG ET AL: "Effect of heat-treatments and hot-isostatic pressing on phase transformation and microstructure in a B / B2 containing gamma-TiAl based alloy ";
• H. CLEMENS ET AL: "Design of Novel B-Solidifying TiAl Alloys with Adjustable B / B2 Phase Fraction and Excellent Hot Workability ";
• Also in the DE 10 2004 056582 A1 and the EP 0 464 366 Such ancestors are described.

Based on the prior art, the present invention has the object to provide a method by which a component having a homogeneous, fine and uniform microstructure can be produced, which component in balanced form, a ductility, strength and creep resistance of the material in all directions substantially the same has desired, high level and can be economically produced with dimensions close to final dimensions.

The invention further aims at a component which, in the case of a targeted phase shaping of the microstructure, has desired mechanical properties, in particular the yield strength R _p0.2 and strength R _m and total elongation A _t in the tensile test at room temperature and at a temperature of 700 ° C. ,

The object is achieved by a method of the type mentioned, in which in a first step, a melt or powder metallurgy manufactured starting material having a chemical composition of in At .-%: Aluminum (Al) 41 to 48 optionally Niobium (Nb) 4 to 9 Molybdenum (Mo) 0.1 to 3.0 Manganese (Mn) to 2.4 Boron (B) to 1.0 Silicon (Si) to 1.0 Carbon (C) to 1.0 Oxygen (O) to 0.5 Nitrogen (N) to 0.5

• h_f = Höhe des Werkstückes nach dem Stauchen
• h_o = Höhe des Werkstückes vor dem Stauchen

oder einem anderen Umformverfahren mit gleich hoher Mindestverformung, insbesondere durch Schmieden bei einer Temperatur im Bereich von 1000 bis 1350°C unter Ausformung eines Bauteiles mit einer nachfolgenden Abkühlung desselben, wobei die Zeitspanne bis zum Erreichen einer Temperatur von 700°C höchstens 10 min beträgt, unterworfen wird, wobei ein Gefüge, welches nur in geringen Teilbereichen dynamisch erholt oder rekristallisiert sein kann, im Wesentlichen jedoch ein Verformungsgefüge mit hohemTitanium and impurities as the remainder,
and this starting material is isostatically pressed to a blank at a pressure of at least 150 MPa at a temperature of at least 1000 ° C after a soak for a period of at least 60 min, after which in a second step the HIP blank of a hot forming by a Rapid massive forming with a speed of greater than 0.4 mm / sec and a deformation by compression measured as local elongation φ of greater than 0.3, where φ is defined as follows: $$\mathrm{\phi }=\ln \left({\mathrm{H}}_{\mathrm{f}}/{\mathrm{H}}_{\mathrm{O}}\right)$$

• h _f = height of the workpiece after swaging
• h _o = height of the workpiece before swaging

or another forming method with equal minimum deformation, in particular by forging at a temperature in the range of 1000 to 1350 ° C to form a component with a subsequent cooling thereof, the time to reach a temperature of 700 ° C is at most 10 minutes, is subjected, wherein a microstructure, which can be dynamically recovered or recrystallized only in small portions, but essentially a deformation structure with high

ALPHA₂:

globular mit einer Korngröße von 1 bis 50 µm mit einem Volumsanteil von 1 bis 50% die vereinzelte, gröbere γ-Lamellen mit einer Dicke von > 100 nm enthalten können

BETA₀:

globular die α₂-Phase umgebend, mit einer Korngröße von 1 bis 25 µm mit einem Volumsanteil von 1 bis 50%

GAMMA:

globular die α₂-Phase umgebend, mit einer Korngröße von 1 bis 25 µm mit einem Volumsanteil von 1 bis 60%

gebildet werden, und in einem nachgeordneten Schritt wahlweise mindestens eine weitere Wärmebehandlung, insbesondere Folgeglühung und/oder Stabilisierungsglühung des Bauteiles, erfolgt (erfolgen kann).Recrystallization energy potential is formed, after which the component for setting desired material properties in a third step is subjected to a heat treatment in which in the eutectoid temperature of the alloy, in particular from 1010 to 1180 ° C in a period of 30 to 1000 min Deformation structure, due to the stored strain energy and the driving force, which consists of the chemical phase imbalance after deformation and cooling, a homogeneous, fine-structure microstructure, consisting of the phases having an ordered atomic structure at room temperature:
GAMMA, BETA ₀ , ALPHA ₂ (γ, β ₀ , α ₂ )
with a shape:

ALPHA ₂ :

Globular with a particle size of 1 to 50 microns with a volume fraction of 1 to 50%, the scattered, coarser γ-lamellae with a thickness of> 100 nm may contain

BETA ₀ :

Globular surrounding the α ₂ -phase, with a grain size of 1 to 25 μm with a volume fraction of 1 to 50%

GAMMA:

Globular surrounding the α ₂ -phase, with a particle size of 1 to 25 μm with a volume fraction of 1 to 60%

are formed, and in a subsequent step optionally at least one further heat treatment, in particular subsequent annealing and / or stabilization annealing of the component takes place (can take place).

With the method according to the invention a variety of technical and economic advantages is achieved.

In the first step of the process, a melt or powder metallurgy produced material requires only compaction by hot isostatic pressing thereof, after which the blank is heated in a second step at an elevated isothermal forging temperature and, as found, at a favorably improved hot working capability of the material of a high speed -Massivumformung at a speed greater than 0.4 mm / sec and a compression ratio φ of greater than 0.3 is subjected. This rapid massive forming of the blank can, surprisingly for the expert, be carried out at elevated temperature with high forming speed, according to the invention a high minimum deformation and subsequent cooling with high cooling rate for a formation of a high, for the time being frozen recrystallization potential in the structure are required.

This recrystallization potential or stored energy resulting from the rapid deformation, which is also formed from the driving force from the chemical phase imbalance, in a third step causes the alloy to undergo a transformation in the region of the eutectoid temperature of the alloy extremely fine-globular microstructure from the phases GAMMA, BETA ₀ , ALPHA ₂ with ordered at room temperature atomic structure with certain phase proportions, which microstructure serves as a favorable fine grain starting structure for a subsequent, achievable by heat treatment (s), provided with regard to desired properties of the material structure formation ,

The object is also achieved by a method of the type mentioned, in which in a first step, a melt or powder metallurgy manufactured starting material having a chemical composition of in At .-%: al 42 to 44.5 optionally Nb 3.5 to 4.5 Not a word 0.5 to 1.5 Mn to 2.2 B 12:05 to 0.2 Si 0001 to 12:01 C 0001 to 1.0 O 0001 to 0.1 N 0.0001 to 12:02

• h_f = Höhe des Werkstückes nach dem Stauchen
• h_o = Höhe des Werkstückes vor dem Stauchen

oder einem anderen Umformverfahren mit gleich hoher Mindestverformung, insbesondere durch Schmieden bei einer Temperatur im Bereich von 1000 bis 1350°C unter Ausformung eines Bauteiles mit einer nachfolgenden Abkühlung desselben, wobei die Zeitspanne bis zum Erreichen einer Temperatur von 700°C höchstens 10 min beträgt, unterworfen wird, wobei ein Gefüge, welches nur in geringen Teilbereichen dynamisch erholt oder rekristallisiert sein kann, im Wesentlichen jedoch ein Verformungsgefüge mit hohem Rekristallisationsenergiepotential aufweist, gebildet wird und wonach das Bauteil in einem dritten Schritt einer Wärmebehandlung unterworfen wird, welche mit einer Zeitspanne von 30 bis 600 min im Bereich der eutektoiden Temperatur der Legierung, insbesondere von 1040 bis 1170°C erfolgt, wobei aus dem Verformungsgefüge eine homogene, feinglobulare Mikrostruktur, bestehend aus den bei Raumtemperatur eine geordnete Atomstruktur aufweisenden Phasen:
GAMMA, BETA₀, ALPHA₂ (γ,β₀,α₂)
mit einer Ausformung:

ALPHA₂:

globular mit einer Korngröße von 1 bis 10 µm mit einem Volumsanteil von 10 bis 35% die vereinzelte, gröbere γ-Lamellen mit einer Dicke von > 100 nm enthalten können

BETA₀:

globular die α₂-Phase umgebend, mit einer Korngröße von 1 bis 10 µm mit einem Volumsanteil von 15 bis 45%

GAMMA:

globular die α₂-Phase umgebend, mit einer Korngröße von 1 bis 10 µm mit einem Volumsanteil von 15 bis 60%

gebildet wird, und wahlweise in einem nachgeordneten Schritt mindestens eine weitere Wärmebehandlung, insbesondere Folgeglühung und/oder
Stabilisierungsglühung des Bauteiles, erfolgt (erfolgen). Titanium and impurities as rest
and this starting material is isostatically pressed to a blank at a pressure of at least 150 MPa at a temperature of at least 1000 ° C after a soak for a period of at least 60 min, after which in a second step the HIP blank of a hot forming by a Fast -Massivumformung with a speed of greater than 0.4 mm / sec and a deformation by compression measured as a local elongation φ of greater than 0.3, where φ is defined as follows: $$\mathit{\phi }=\mathit{ln}\left({\mathit{H}}_{\mathit{f}}/{\mathit{H}}_{\mathit{O}}\right)$$

• h _f = height of the workpiece after swaging
• h _o = height of the workpiece before swaging

or another forming method with equal minimum deformation, in particular by forging at a temperature in the range of 1000 to 1350 ° C to form a component with a subsequent cooling thereof, the time to reach a temperature of 700 ° C is at most 10 minutes, wherein a microstructure, which may be dynamically recovered or recrystallized only in small portions, but essentially has a deformation structure with high Rekristallisationsenergiepotential is formed, and then the component is subjected in a third step to a heat treatment, which with a period of 30 up to 600 min in the region of the eutectoid temperature of the alloy, in particular from 1040 to 1170 ° C., whereby from the deformation microstructure a homogeneous, fine-globular microstructure consisting of the phases having an ordered atomic structure at room temperature:
GAMMA, BETA ₀ , ALPHA ₂ (γ, β ₀ , α ₂ )
with a shape:

ALPHA ₂ :

Globular with a particle size of 1 to 10 microns with a volume fraction of 10 to 35%, the isolated, coarser γ-lamellae with a thickness of> 100 nm may contain

BETA ₀ :

globular surrounding the α ₂ -phase, with a grain size of 1 to 10 μm with a volume fraction of 15 to 45%

GAMMA:

Globular surrounding the α ₂ -phase, with a grain size of 1 to 10 μm with a volume fraction of 15 to 60%

is formed, and optionally in a subsequent step, at least one further heat treatment, in particular subsequent annealing and / or
Stabilizing annealing of the component, carried out (done).

Such, limited in the concentrations of the elements, chemical composition of the material can intensify a achieved by the process parameters, favorable behavior in terms of structural transformation and education.

The fine grain formation in the material, created by the above method, although in isotropic microstructure morphology causes increased strength within narrow limits, but the toughness and the creep resistance of the material for certain applications can not be considered sufficient. However, this fine grain structure is at best a prerequisite for obtaining a substantially fine, homogeneous structure in further annealing treatments for setting desired, mechanical properties of the component.

ALPHA₂:

globular übersättigt, gegebenenfalls gering feine γ-Lamellen enthaltend, mit einer Korngröße von 5 µm bis 100 µm mit einem Volumsanteil von 25% bis 98%

BETA₀:

globular, mit einer Korngröße von 1 µm bis 25 µm mit einem Volumsanteil von 1% bis 25%

GAMMA:

globular, mit einer Korngröße von 1 µm bis 25 µm mit einem Volumsanteil von 1% bis 50%

gebildet wird.In order to achieve in particular the high-temperature properties of the material with respect to an improvement in ductility or an increase in toughness and an increase in creep resistance, it is provided according to the invention to subject the component with a fine grain structure created in the third step for setting optimized high-temperature material properties of at least one subsequent annealing which subsequent annealing in the region close to the alpha transus temperature (T _α ) of the alloy in three-phase space (alpha, beta, gamma) during a period of at least 30 to 6000 min, after which the part in a Period of less than 10 min to a temperature of 700 ° C and then further, preferably in air, cooled and thus a Phasenausformung:

ALPHA ₂ :

Globular supersaturated, possibly containing low-fine γ-lamellae, with a particle size of 5 μm to 100 μm with a volume fraction of 25% to 98%

BETA ₀ :

globular, with a particle size of 1 μm to 25 μm with a volume fraction of 1% to 25%

GAMMA:

globular, with a particle size of 1 μm to 25 μm with a volume fraction of 1% to 50%

is formed.

In particular, the supersaturated ALPHA ₂ grains and a fine but non-optimized microstructural shape give low material ductility and toughness at high strength values. Improved mechanical properties of the material can be achieved by means of a narrowed chemical composition, but the property profile is oriented only to specific uses.

Although a narrowed chemical composition of the material, as stated above, can be used to achieve favorable proportions of the microstructural constituents with narrower dimensions and narrower content limits, the resulting advantages are reflected in a certain refinement of the mechanical property values; Essentially, however, the prerequisites for optimizing the high-temperature behavior of a component made of a titanium-aluminum base alloy are created in a highly advantageous manner.

A choice of annealing time at a post-anneal close to the alpha transus temperature (T _α ) can be made with a view to setting desired phase amounts and grain sizes. For example, the β-phase is generally reduced as the annealing time increases.

After a thermal treatment in the Alpha-Transus area and a forced Cooling, the structural phases essentially have a disordered atomic structure.

ALPHA₂ / GAMMA:

Lamellarkorn mit einer Korngröße von 5 µm bis 100 µm mit einem Volumsanteil von 25% bis 98% mit einer (α₂/γ) Lamellen-Feinstruktur vorzugsweise mit einem mittleren Lamellenabstand von 10 nm bis 1 µm

BETA₀:

globular, mit einer Korngröße von 1 µm bis 25 µm mit einem Volumsanteil von 1% bis 25%

GAMMA:

globular, mit einer Korngröße von 1 µm bis 25 µm mit einem Volumsanteil von 1% bis 50%

erfolgt, können Gefügeausformungen mit wesentlich verbesserten mechanischen Hochtemperatureigenschaften des Werkstoffes erreicht werden.If, in the production process, the component is subjected to at least one stabilization annealing after a subsequent annealing, which in a temperature range of 700 ° C. to 1000 ° C., if necessary above the application temperature of the component with a duration of 60 minutes to 1000 minutes and a subsequent slow or furnace cooling at a rate of less than 5 ° C / min, preferably less than 1 ° C / min, for the purpose of adjusting or shaping the microstructural constituents:

ALPHA ₂ / GAMMA:

Lamellar grain with a grain size of 5 .mu.m to 100 .mu.m with a volume fraction of 25% to 98% with a (α ₂ / γ) lamellar fine structure, preferably with a mean fin spacing of 10 nm to 1 .mu.m

BETA ₀ :

globular, with a particle size of 1 μm to 25 μm with a volume fraction of 1% to 25%

GAMMA:

globular, with a particle size of 1 μm to 25 μm with a volume fraction of 1% to 50%

structural conformations with significantly improved high-temperature mechanical properties of the material can be achieved.

By means of a stabilization annealing with a slow cooling, in which sufficient atomic diffusion is maintained, the supersaturated ALPHA ₂ grains are converted into a lamellar ALPHA ₂ / GAMMA structure without any significant change in grain size. A lamellar structure in the formerly supersaturated structural grains greatly improves the creep resistance of the material at high temperatures of around 700 ° C in the temperature range.

ALPHA₂:

globular übersättigt mit einer Korngröße von 1 µm bis 50 µm mit einem Volumsanteil von 1% bis 50%, die vereinzelte, gröbere γ-Lamellen mit einer Dicke von > 100 nm enthalten können

BETA₀:

globular die α₂-Phase umgebend, mit einer Korngröße von 1 µm bis 25 µm mit einem Volumsanteil von 1% bis 50%

GAMMA:

globular die α₂-Phase umgebend, mit einer Korngröße von 1 µm bis 25 µm mit einem Volumsanteil von 1% bis 60%

erreicht, vorzugsweise eingestellt mit einem Verfahren gemäß Anspruch 1 oder 3, wobei das Material folgende, mechanische Eigenschaften im Bereich von:

• Festigkeit und Bruchdehnung bei Raumtemperatur:
  • ∘ R_p0.2: 650 bis 910 MPa
  • ∘ R_m: 680 bis 1010 MPa
  • ∘ A_t: 0.5% bis 3%
• Festigkeit und Bruchdehnung bei 700°C:
  • ∘ R_p0.2: 520 bis 690 MPa
  • ∘ R_m: 620 bis 970 MPa
  • ∘ A_t: 1% bis 3.5%

aufweist.The further object of the invention is provided with a dimensionally near-dimensionally dimensioned component made of a titanium-aluminum base alloy having a chemical composition according to claim 1 or 2, prepared with a microstructure of the material consisting of the phases having an ordered atomic structure at room temperature:
GAMMA, BETA ₀ , ALPHA ₂ (γ, β ₀ , α ₂ )
with a shape:

ALPHA ₂ :

Globular supersaturated with a particle size of 1 .mu.m to 50 .mu.m with a volume fraction of 1% to 50%, which may contain isolated, coarser γ-lamellae with a thickness of> 100 nm

BETA ₀ :

globular surrounding the α ₂ -phase, with a grain size of 1 μm to 25 μm with a volume fraction of 1% to 50%

GAMMA:

globular surrounding the α ₂ -phase, with a grain size of 1 μm to 25 μm with a volume fraction of 1% to 60%

achieved, preferably adjusted by a method according to claim 1 or 3, wherein the material has the following mechanical properties in the range of:

• Strength and elongation at room temperature:
  • _P R _p0.2 : 650 to 910 MPa
  • ∘ R _m : 680 to 1010 MPa
  • ∘ A _t : 0.5% to 3%
• Strength and elongation at 700 ° C:
  • _P R _p0.2 : 520 to 690 MPa
  • ∘ R _m : 620 to 970 MPa
  • ∘ A _t : 1% to 3.5%

having.

This created with high efficiency of manufacturing component has a fine, globular, homogeneous microstructure with the same property profile in all directions of the material, which is advantageously used for a variety of applications.

ALPHA₂:

globular übersättigt, gegebenenfalls gering feine γ-Lamellen enthaltend, mit einer Korngröße von 5 µm bis 80 µm mit einem Volumsanteil von 50% bis 95%

BETA₀:

globular, mit einer Korngröße von 1 µm bis 20 µm mit einem Volumsanteil von 31% bis 25%

GAMMA:

globular, mit einer Korngröße von 1 µm bis 20 µm mit einem Volumsanteil von 1% bis 28%

vorzugsweise eingestellt nach einem Verfahren gemäß Anspruch 4 oder 5 gebildet ist, wobei das Material folgende, mechanische Eigenschaften im Bereich von:

• Festigkeit und Bruchdehnung (nach ASTM E8M, EN 2002-1) bei Raumtemperatur:
  • ∘ R_p0.2: 650 bis 940 MPa
  • ∘ R_m: 730 bis 1050 MPa
  • ∘ A_t: 0.2% bis 2%
• Festigkeit und Bruchdehnung bei 700°C:
  • ∘ R_p0.2: 430 bis 620 MPa
  • ∘ R_m: 590 bis 940 MPa
  • ∘ A_t: 1% bis 2.5%

aufweist.In order to achieve an improvement in the mechanical material properties, in particular an increase in creep resistance, it is advantageous if the component is made with a structure of the material:

ALPHA ₂ :

globular supersaturated, optionally containing small fine γ-lamellae, with a particle size of 5 μm to 80 μm with a volume fraction of 50% to 95%

BETA ₀ :

globular, with a grain size of 1 μm to 20 μm with a volume fraction of 31% to 25%

GAMMA:

globular, with a grain size of 1 μm to 20 μm with a volume fraction of 1% to 28%

preferably adjusted according to a method according to claim 4 or 5, wherein the material has the following mechanical properties in the range of:

• Strength and elongation at break (according to ASTM E8M, EN 2002-1) at room temperature:
  • _P R _p0.2 : 650 to 940 MPa
  • ∘ R _m : 730 to 1050 MPa
  • ∘ A _t : 0.2% to 2%
• Strength and elongation at 700 ° C:
  • _P R _p0.2 : 430 to 620 MPa
  • ∘ R _m : 590 to 940 MPa
  • ∘ A _t : 1% to 2.5%

having.

ALPHA₂ / GAMMA:

Lamellarkorn mit einer Korngröße von 5 µm bis 100 µm mit einem Volumsanteil von 25% bis 98% mit einer (α₂/γ) Lamellen-Feinstruktur vorzugsweise mit einem mittleren Lamellenabstand von 10 nm bis 1 nm

BETA₀:

globular, mit einer Korngröße von 0.5 µm bis 25 µm mit einem Volumsanteil von 1% bis 25%

GAMMA:

globular, mit einer Korngröße von 0.5 µm bis 25 µm mit einem Volumsanteil von 1% bis 50%

• vorzugsweise eingestellt nach einem Verfahren gemäß Anspruch 6 oder 7 gebildet ist, wobei das Material folgende, mechanische Eigenschaften im Bereich von:
  • Festigkeit und Bruchdehnung (nach ASTM E8M, EN 2002-1) bei Raumtemperatur:
    • ∘ R_p0.2: 710 bis 1020 MPa
    • ∘ R_m: 800 bis 1250 MPa
    • ∘ A_t: 0.8% bis 4%
  • Festigkeit und Bruchdehnung bei 700°C:
    • ∘ R_p0.2: 540 bis 760 MPa
    • ∘ R_m: 630 bis 1140 MPa
    • ∘ A_t: 1 % bis 4.5%

aufweist.A particular advantage in terms of ductility, strength and creep resistance of the material in all directions to the same extent at a high level is achieved if the component with a structure of the material consisting of the components with a shape:

ALPHA ₂ / GAMMA:

Lamellar grain with a grain size of 5 .mu.m to 100 .mu.m with a volume fraction of 25% to 98% with a (α ₂ / γ) lamellar fine structure, preferably with a mean fin spacing of 10 nm to 1 nm

BETA ₀ :

globular, with a particle size of 0.5 μm to 25 μm with a volume fraction of 1% to 25%

GAMMA:

globular, with a particle size of 0.5 μm to 25 μm with a volume fraction of 1% to 50%

• preferably adjusted according to a method according to claim 6 or 7, wherein the material has the following mechanical properties in the range of:
  • Strength and elongation at break (according to ASTM E8M, EN 2002-1) at room temperature:
    • _P R _p0.2 : 710 to 1020 MPa
    • ∘ R _m : 800 to 1250 MPa
    • ∘ A _t : 0.8% to 4%
  • Strength and elongation at 700 ° C:
    • _P R _p0.2 : 540 to 760 MPa
    • ∘ R _m : 630 to 1140 MPa
    • ∘ A _t : 1% to 4.5%

having.

In the following, the invention will be explained in more detail with reference to images comprising only one alloy composition.

Fig. 1

Gefügeausbildung in Abhängigkeit von der Temperatur und der Aluminiumkonzentration mit vom Fachmann verwendeten Temperaturbereichsangaben (Prinzipschaubild)

Fig. 2

Gefüge der Ti-AI-Basislegierung nach einer Massivumformung und anschließender Abkühlung

Fig. 3

Gefüge der Legierung nach einer Glühung im Bereich der eutektoiden Temperatur (T_eu) und Abkühlung

Fig. 4

Gefüge der Legierung nach einer Glühung bei Alpha-Transus-Temperatur (T_α)

Fig. 5

Gefüge der Legierung nach einer Stabilisierungsglühung

Show it:

Fig. 1

Structure formation as a function of the temperature and the aluminum concentration with temperature range data used by the person skilled in the art (schematic diagram)

Fig. 2

Microstructure of the Ti-Al base alloy after massive forming and subsequent cooling

Fig. 3

Structure of the alloy after annealing at the eutectoid temperature (T _eu ) and cooling

Fig. 4

Microstructure of Alloy After Annealing at Alpha Transus Temperature (T _α )

Fig. 5

Structure of the alloy after stabilization annealing

In Fig. 1 schematically the microstructures of titanium-aluminum base alloys are shown as a function of the temperature and the aluminum concentration. Furthermore, the temperature data used by the expert can be seen.

The in the Fig. 2 to Fig. 5 The microstructures shown are from a test series with an alloy Ti, 43.2 at.% Al, 4 at.% Nb, 1 at.% Mo, 0.1 at.% B.

This alloy has a eutectoid temperature of T _eu 1165 ° C ± 7 ° C and an alpha transus temperature T _α = 1 243 ° C ± 7 ° C, which temperatures were determined by differential thermal analysis.

The micrographs were taken at 200X magnification on the scanning electron microscope in electron backscatter contrast.

Fig. 2 shows the structure of the material after deformation in a die with a degree of deformation of φ = 0.7 with a forming speed of 1.0 mm / sec and a cooling in air. As a result of forging comprises after cooling of the part of this, a typical directed deformation texture and shows as components directed GAMMA-BETA ₀ -ALPHA ₂ grains.

Fig. 3 shows the structure of the deformed part after a heat treatment in the region of the eutectioden temperature (T _eu ) in the present case at 1150 ° C, followed by a cooling.

The microstructure consisted of globular ALPHA ₂ grains with a particle size (measured as the diameter of the smallest circumscribed circle) of 3.2 μm ± 1.9 μm with a volume fraction of approximately 25% from globular BETA ₀ grains with a particle size of 3.7 μm ± 2.1 μm with a volume fraction of about 26% and globular GAMMA grains with a grain size of 5.7 μm ± 2.4 μm with a volume fraction of 49%.

In Fig. 4 is the structure of the deformed and subsequently annealed at 1150 ° C and cooled part after a subsequent annealing in the range of the alpha transus temperature (T _α ) in the given case at a temperature of 1240 ° C and a cooling of this to 700 ° C in 5 min and further cooling in air.

The microstructural constituents were: ALPHA ₂ granules with a particle size of 11.0 μm ± 5.8 μm with a volume fraction of 73%, globular BETA ₀ grains with a particle size of 4.5 μm ± 2.6 μm with a volume fraction of 11% and globular GAMMA grains with a grain size of 4.2 μm ± 2.2 μm with a volume fraction of 16%.

Fig. 5 shows the structure of the deformed part after a fine grain annealing in the eutectoid temperature range (T _eu ), followed by a high-temperature annealing in the (α + β + γ) phase space or an alpha transus annealing (T _α ) at 1240 ° C and a forced cooling stabilizing annealing in a given case at 875 ° C followed by slow cooling at a rate of 2 ° C / min.

It should be noted at this point that the microstructure of the microstructure and the property profile of the material can be adjusted by varying the annealing temperature and / or the annealing time.

After the above heat treatment, the structure consisted of globular ALPHA ₂ / GAMMA grains with lamellar α / γ structure with a grain size of 7.1 μm ± 3.8 μm with a volume fraction of 64% from globular BETA ₀ grains with a grain size of 2.3 μm ± 2.2 μm with a volume fraction of 13% and of globular GAMMA phases with a grain size of 2.7 μm ± 2.1 μm with a volume fraction of 23%.

Like the other samples from series of tests, the most important mechanical properties were measured on this part. At room temperature, the strength _values R _p0.2 exceeded 720 MP, R _m exceeded 810 MP and the elongation at break exceeded 1.6%.

At 700 ° C., a value A _p of less than 0.65% was determined in the creep test (ASTME139 or EN2005-5) at a test voltage in the sample of 250 MPa and a stress duration of 100 hours.

Claims (9)

1. Method for the production of a component made of a titanium-aluminum base alloy, in which, in a first step, a primary material which has been produced by melting or powder metallurgy and has a chemical composition in At.-% of: Aluminum (Al) 41 to 48 optionally Niobium (Nb) 4 to 9 Molybdenum (Mo) 0.1 to 3.0 Manganese (Mn) to 2.4 Boron (B) to 1 .0 Silicon (Si) to 1.0 Carbon (C) to 1.0 Oxygen (0) to 0.5 Nitrogen (N) to 0.5 Titanium and impurities as the remainder,
   wherein this primary material is isostatically pressed into a blank under a pressure increase to at least 150 MPa at a temperature of at least 1000 °C after heating for a period of at least 60 min, whereupon, in a second step, the HIP blank is subjected to a thermoforming process by means of rapid-forming though a rapid mass forming at a rate greater than 0.4 mm/sec and a forming by compression measured as a local strain ϕ of greater than 0.3, where ϕ is defined as follows: $$\mathrm{\Phi }=\ln \left({\mathrm{h}}_{\mathrm{f}}/{\mathrm{h}}_{\mathrm{o}}\right)$$

   

   h_f = height of the workpiece after compression

   h_o = height of the workpiece before compression

   or another forming method with an equally high minimum forming, in particular by forging at a temperature in the range from 1000 to 1350 °C, to form a component with a subsequent cooling thereof, wherein the time until a temperature of 700 °C. is reached is at most 10 min, wherein a structure which may only be dynamically recovered or recrystallized in small subregions, but substantially has a forming structure with high recrystallization energy potential, wherein the component is subjected to heat treatment in a third step for the adjustment of desired material properties, which in the region of the eutectoid temperature (T_eu) of the alloy, in particular from 1010 to 1180 °C, over a period of 30 to 1000 min from the forming structure, due to the stored forming energy and the driving force to the structural change, which consists of the chemical phase equilibrium after the forming and cooling, after cooling in air, a homogeneous fine-globular microstructure, formed from the phases having an ordered atomic structure at room temperature:
   GAMMA, BETA₀, ALPHA₂ (γ, β₀, α₂)
   having a formation:

   ALPHA₂: globular with a grain size of 1 to 50 µm with a volume fraction of 1 to 50%, which may contain isolated, coarser γ-lamellae with a thickness > 100 nm BETA₀: globular surrounding the α₂ phase with a grain size of 1 to 25 µm with a volume fraction of 1 to 50%

   GAMMA: Globular surrounding the α₂ phase with a grain size of 1 to 25 µm with a volume fraction of 1 to 50%

   wherein, in a subsequent step, at least one further heat treatment, in particular subsequent annealing and/or stabilizing annealing of the component, takes place.
2. Method for the production of a component from a titanium-aluminum base alloy, wherein, in a first step, a primary material which has been produced by melting or powder metallurgy and has a chemical composition in At.-% of at least. Al 42 to 44.5 optionally Nb 3.5 to 4.5 Mo 0.5 to 1.5 Mn to 2.2 B 0.05 to 0.2 Si 0.001 to 0.01 C 0.001 to 1.0 O 0.001 to 0.1 N 0.0001 to 0.02 Titanium and impurities as the remainder,
   wherein this preliminary material is isostatically pressed into a blank at a pressure increase of at least 150 MPa at a temperature of at least 1000 °C after heating for a period of at least 60 minutes, whereupon, in a second step, the hot blank is subjected to a hot forming process by means of rapid-forming though rapid mass forming at a rate greater than 0.4 mm/sec and forming by compression measured as a local strain ϕ greater than 0.3, where ϕ is defined as follows: $$\mathrm{\Phi }=\ln \left({\mathrm{h}}_{\mathrm{f}}/{\mathrm{h}}_{\mathrm{o}}\right)$$

   

   h_f = height of the workpiece after compression

   h_o = height of the workpiece before compression

   or another forming method with an equally high minimum forming, in particular by forging at a temperature in the range from 1000 to 1350° C to form a component with subsequent cooling thereof, wherein the time until a temperature of 700 °C is reached is at most 10 min, wherein a structure which may be dynamically recovered or recrystallized only in small subregions, but essentially has a forming structure with a high recrystallization energy potential, after which the component is subjected to heat treatment in a third step in the range of the eutectoid temperature (T_eu) of the alloy, in particular from 1040 to 1170 °C over a period of 30 to 600 min, for adjusting the desired material properties in a third step, wherein from the forming structures after cooling in air, a homogeneous, fine-lobular microstructure is produced consisting of the phases having an ordered atomic structure at room temperature:
   GAMMA, BETA₀, ALPHA₂ (γ, β₀, α₂)
   having a formation:

   ALPHA₂: globular with a grain size of 1 to 10 µm with a volume fraction of 1 to 35%, which may contain isolated coarser γ-lamellae with a thickness of > 100 nm BETA₀: globular surrounding the α₂ phase with a grain size of 1 to 10 µm with a volume fraction of 15 to 45%

   GAMMA: globular surrounding the α₂ phase with a grain size of 1 to 10 µm with a volume fraction of 15 to 60%

   wherein, optionally, at least one further heat treatment, in particular subsequent annealing and/or stabilizing annealing of the component, takes place in a subordinate step.
3. Method according to claim 1, wherein the component with a fine structure produced in the third step for the adjustment of optimum high temperature material properties is subjected to at least a following annealing in the range near the alpha transus temperature (T_o) of the alloy in the thee phases (Alpha, Beta, Gamma) during a time period of at least 30 to maximum of 6000 min, after which the part is cooled to a temperature of 700 °C in a period of less than 10 min and then further preferably in air, and a phase forming in this way:

   ALPHA₂: globular supersaturated, optionally containing small fine γ-lamellae, with a grain size of 5 to 100 µm with a volume fraction of 25 to 98%

   BETA_o: globular, with a grain size of 1 to 25 µm with a volume fraction of 1 to 25% GAMMA: globular, with a grain size of 1 to 25 µm with a volume fraction of 1 to 50%.
4. Method according to claim 2, wherein the component having a fine structure created in the third step for the adjustment of optimized high temperature properties, is subjected to at least one subsequent annealing which is carried out in the region close to the alpha transus temperature (T_o) of the alloy in the three-phase space (Alpha, Beta, Gamma) for a period of at least 30 to a maximum of 6000 min, after which the part is cooled to a temperature of 700 °C over a period of less than 10 min and then further, preferably in air, and a phase forming in such a way:

   ALPHA₂: globular super saturated, optionally containing small fine γ-lamellae, with a grain size of 5 to 80 µm with a volume fraction of 50 to 98%

   BETA_o: globular, with a grain size of 1 to 20 µm with a volume fraction of 1 to 25% GAMMA: globular, with a grain size of 1 to 20 µm with a volume fraction of 1 to 28%.
5. Method according to claim 3, wherein the component is subjected to at least one stabilizing annealing after a subsequent annealing according to claim 3, which is carried out in a temperature range from 700 to 1000 °C, possibly above the application temperature of the component with a duration of 60 to 1000 min, and a subsequent slow or furnace cooling at a rate of less than 5 °C/min, preferably less than 1 °C/min, for setting or shaping the structural constituents:

   ALPHA₂/GAMMA: Lamellar grain with a grain size of 5 to 100 µm with a volume fraction of 25 to 98%, and an (α₂/γ) lamellar fine structure, preferably with a mean lamellar spacing of 10 nm to 1 µm

   BETA_o: globular, with a grain size of 1 to 25 µm with a volume fraction of 1 to 25% GAMMA: globular, with a grain size of 1 to 25 µm with a volume fraction of 1 to 50%.
6. Method according to claim 4, wherein the component is subjected to at least one stabilizing annealing after a subsequent annealing according to claim 4, which is carried out in a temperature range of from 700 to 1000 °C, possibly above the application temperature of the component with a duration of 60 to 1000 min, and followed by slow or furnace cooling at a rate of less than 5 °C/min, preferably of less than 1 °C/min, for setting or shaping the structural components:

   ALPHA₂/GAMMA: Lamellar grain with a grain size of 5 to 80 µm with an (α₂/γ) lamellar fine structure, preferably with a mean lamellar spacing of 10 to 30 nm and with a volume fraction of 45 to 90%

   BETA_o: globular, with a grain size of 1 to 20 µm with a volume fraction of 1 to 25% GAMMA: globular, with a grain size of 1 to 20 µm with a volume fraction of 1 to 25%.
7. Component made of a titanium-aluminum base alloy with a chemical composition according to claim 1 or 2, produced with dimensions close to the final dimensions, obtainable by a method according to claim 1 or 2 with a structure of the material comprising the ordered atomic structure at room temperature phases:
   
   GAMMA, BETA₀, ALPHA₂ (γ, β₀, α₂)
   with a formation:

   ALPHA₂: globular with a grain size of 1 to 50 µm with a volume fraction of 1 to 50%, which may contain isolated, coarser γ-lamellae with a thickness > 100 nm BETA_o: globular surrounding the α₂ phase, with a grain size of 1 to 25 µm with a volume fraction of 1 to 50%

   GAMMA: globularly surrounding the α₂ phase, with a grain size of 1 to 25 µm, with a volume fraction of 1 to 60%,

   obtainable by a method according to claim 1 or 2, wherein the material has the following mechanical properties in the range of:

   • Strength and elongation at break at room temperature:

   ∘ R_p0.2: 650 to 910 MPa

   ∘ R_m: 680 to 1010 Mpa

   ∘ A_t: 0.5 to 3%

   • Strength and elongation at break at 700 °C:

   R_p0.2: 520 to 690 MPa

   ∘ R_m: 620 to 970 MPa

   ∘ A_t: 1 to 3.5%.
8. Component made of a titanium-aluminum base alloy with a chemical composition according to claim 1 or 2, produced with dimensions close to the final dimensions, with a microstructure of the material consisting of:

   ALPHA₂: globular super saturated, optionally containing small fine γ-lamellae, with a grain size of 5 to 80 µm with a volume fraction of 50 to 95%

   BETA_o: globular, with a grain size of 1 to 20 µm with a volume fraction of 1 to 25%

   GAMMA: globular, with a grain size of 1 to 20 µm with a volume fraction of 1 to 28% adjusted by a method according to claim 3 or 4, wherein said material has the following mechanical properties in the range of:

   • Strength and elongation at break (according to ASTM E8M, EN 2002-1) at room temperature:

   ∘ R_p0.2: 650 to 940 MPa

   ∘ R_m: 730 to 1050 MPa

   ∘ A_t: 0.2 to 2%

   • Strength and elongation at break at 700 °C:

   ∘ R_p0.2: 430 to 620 MPa

   ∘ R_m: 590 to 940 MPa

   ∘ A_t: 1 to 2.5%.
9. Component made of a titanium-aluminum base alloy with a chemical composition according to claim 1 or 2, produced with dimensions close to the final dimensions, with a microstructure of the material consisting of the components with a shaping:

   ALPHA₂/GAMMA: Lamellar grain with a grain size of 5 to 100 µm with a volume fraction of 25 to 98% with an (α₂/γ) lamellar fine structure, preferably with a mean lamellar spacing of 10 to 1 nm

   BETA_o: globular, with a grain size of 0.5 to 25 µm with a volume fraction of 1 to 25%

   GAMMA: globular, with a grain size of 0.5 to 25 µm with a volume fraction of 1 to 50% adjusted by a method according to claim 5 or 6, wherein the material has the following mechanical properties in the range of:

   • Strength and elongation at break (according to ASTM E8M, EN 2002-1) at room temperature:

   ∘ R_p0.2: 710 to 1020 MPa

   ∘ R_m: 800 to 1250 MPa

   ∘ A_t: 0.8 to 4%

   • Strength and elongation at break at 700 °C:

   ∘ R_p0.2: 540 to 760 MPa

   ∘ R_m: 630 to 1140 MPa

   ∘ A_t: 1 to 4.5% having.

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