EP0464366A1 - Process for producing a work piece from an alloy based on titanium aluminide containing a doping material - Google Patents

Process for producing a work piece from an alloy based on titanium aluminide containing a doping material Download PDF

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EP0464366A1
EP0464366A1 EP91108605A EP91108605A EP0464366A1 EP 0464366 A1 EP0464366 A1 EP 0464366A1 EP 91108605 A EP91108605 A EP 91108605A EP 91108605 A EP91108605 A EP 91108605A EP 0464366 A1 EP0464366 A1 EP 0464366A1
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Prior art keywords
workpiece
temperature
cast body
cooling
casting
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German (de)
French (fr)
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EP0464366B1 (en
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Mohamed Dr. Nazmy
Markus Staubli
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ABB Asea Brown Boveri Ltd
ABB AB
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ABB Asea Brown Boveri Ltd
Asea Brown Boveri AB
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    • 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
    • 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

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  • the invention is based on a method for producing a workpiece from a dopant-containing alloy based on titanium aluminide.
  • High-temperature alloys for thermal machines based on the intermetallic compound TiAI which are suitable for the production of cast and forged components and which can supplement and partially replace the conventional nickel-based superalloys.
  • the invention relates to the melting and casting of alloys doped on the intermetallic compound TiAI with further additives and to the thermal and thermomechanical further processing to usable workpieces with good mechanical properties.
  • Intermetallic compounds of titanium with aluminum have some interesting properties which make them appear attractive as construction materials in the medium and higher temperature range. Among other things, this includes their low density compared to superalloys, which only reaches about 1/2 of the value for Ni superalloys. Their technical usability in the present form, however, stands in the way of their brittleness. The former can be improved by additives, whereby higher strength values are also achieved. As possible and in part already introduced intermetallic compounds, nickel aluminides, nickel silicides and titanium aluminides are known as construction materials.
  • the shape of the intermetallic phases based on titanium aluminides presents a certain problem. Because of the high affinity of the elements involved for oxygen, in particular that of titanium, the production of molded parts by casting is difficult. Poor mold filling capacity, porosity and cavities are the consequences. In addition, the properties of the cast structure cannot be improved to the desired extent by subsequent heat treatments. On the other hand, classic hot forming is opposed by the comparatively poor ductility in the lower temperature range.
  • the invention is based on the object of specifying a method for producing a workpiece from a dopant-containing alloy based on titanium aluminide, which leads to a material having high oxidation and corrosion resistance, high heat resistance and sufficient ductility.
  • the yield point of the material to be forged was around 260 MPa at 1100 ° C.
  • the linear rate of deformation (punch speed of the forging press) v was 0.1 mm / s at the start of the forging process.
  • the pressing forces required for the upsetting were of medium size. In the present case, they were approximately 750 kN, which corresponded to an initial pressure of approximately 300 MPa.
  • the forging die consisted of the Mo alloy containing small amounts of Ti and Zr.
  • the flow limit of the workpiece was approx. 200 MPa at 1150 ° C.
  • the workpiece had a Vickers hardness HV of an average of 336 kg / mm 2 .
  • the melt was poured into ingots approximately 55 mm in diameter and 65 mm high.
  • the ingots were then annealed in an argon atmosphere for 10 hours at a temperature of 1100 ° C., cooled and mechanically processed to remove the casting skin.
  • the alloy was homogenized by the annealing. Depending on the alloy composition, a suitable homogenization was achieved at temperatures between 1000 and 1150 ° C and annealing times between one and thirty hours. Then the cylindrical workpieces were encapsulated, hot isostatically pressed and forged at a temperature of 1150 ° C.
  • the deformation ⁇ was 0.69 (height decrease 50%), the observed yield point was approx. 380 MPa.
  • the rate of deformation (punch speed) was 0.1 mm / s.
  • the forging process was carried out essentially isothermally at a temperature of 1120 ° C., a flow limit of 250 MPa being observed on average.
  • the rate of deformation (punch speed) at the start of each forging operation was approximately 0.1 to 0.2 mm / s.
  • the base part was compressed by a further 20% decrease in height in the longitudinal axis of the airfoil.
  • the workpiece was then cooled to below 500 ° C. at a rate of 300 ° C./h and, after cooling, tempered at 800 ° C. for 1 hour. With this, the almost final shape of the turbine blade was achieved, apart from milling the grooves on the fir tree base.
  • a prismatic ingot with a rectangular cross-section was cast with a thickness of approx. 40 mm, 90 mm in width and 250 mm in length.
  • the cast skin was removed by planing and the ingot was encapsulated in soft steel and hot-isostatically pressed at 1260 ° C. for 3 h under a pressure of 120 MPa.
  • the first forming was a compression (isothermal forging) in the longer transverse direction (upright) of approx. 33%, so that the ingot assumed an approximately square cross-section with a side length of approx. 60 mm.
  • This operation was carried out at a temperature of 1150 ° C under an argon atmosphere. Then the ingot was hot rolled in the other transverse direction at the same temperature, taking approximately the original rectangular cross-sectional shape but with reduced dimensions. After intermediate annealing at 1200 ° C for 1 h under an argon atmosphere, the ingot was deformed by hot rolling (40% reduction in cross-section) at 1050 ° C into a rod with a rectangular profile. During the operations, a hot stretch limit of approximately 240 MPa was observed at 1150 ° C. The structure of the finished rod was fine-grained and homogeneous. The Vickers hardness HV was increased by approx. 25% compared to the as-cast state.
  • a body was cast as a stepped cylinder.
  • the total height was 220 mm, the height of the smaller diameter 120 mm, that of the larger 100 mm, the diameters 60 mm and 100 mm.
  • the cast blank was annealed at 1050 ° C, overturned (removal of the cast skin) and encapsulated in an all-round sleeve made of soft steel and hot isostatically pressed according to the previous examples. Then the block was first compressed in the longitudinal direction with a 30% decrease in height at 1150 ° C. and pressed several times in the transverse directions in such a way that an oval cross section was produced in the leaf section. Intermediate annealing was carried out at 1200 ° C.
  • the pre-forged blank with an oval cross-section in the sheet section was placed in the die of a forging press and in several stages up to Deformed reaching the above leaf profile.
  • the forging process was carried out essentially isothermally at a temperature of 1150 ° C. A flow limit of 200 MPa on average was observed at this temperature.
  • the rate of deformation (punch speed) at the start of the drop forging operations was approximately 0.2 mm / s.
  • the remaining process steps were analogous to Example 4.
  • the tempering was carried out at a temperature of 750 ° C. for 2 hours.
  • the structure of the finished turbine blade was fine-grained and homogeneous.
  • the Vickers hardness HV was 15% higher than the as-cast state.
  • B generally has a strong toughness-increasing effect in combination with other strength-increasing elements.
  • the loss of ductility caused by alloying W could be practically compensated for by adding only 0.5 at.% B. Additions higher than 1 at.% B are not necessary.
  • the area of application of the modified titanium aluminides advantageously extends to temperatures between 600 and 1000 C.
  • the invention is not restricted to the exemplary embodiments.
  • the workpiece is essentially forged isothermally, and after the isothermal forging it has the shape of a gas turbine blade.
  • the workpiece is essentially forged isothermally and, after the isothermal forging, is subjected to a further hot-forming process with up to 40% reduction in cross-section, the latter advantageously consisting of hot rolling.

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

Abstract

The process is used to produce a workpiece from a dopant-containing alloy based on titanium aluminide. With this process it is intended to produce a workpiece having high resistance to oxidation and to corrosion, high heat stability and adequate ductility. This is achieved by the following process steps: - Melting the alloy, - Casting the melt to give a casting, - Cooling the casting to room temperature and removing its skin and its scale layer, - Hot isostatic pressing of the descaled casting at a temperature between 1200 and 1300 DEG C and a pressure between 100 and 150 MPa, - Cooling the casting which has been subjected to hot isostatic pressing, - Heating the cooled casting to temperatures of 1050 to 1200 DEG C, - Isothermally working the casting once or repeatedly at this temperature for shaping and improving the microstructure, - Cooling the worked casting to room temperature and - Processing of the worked casting with removal of material to give the workpiece. <IMAGE>

Description

Technisches GebietTechnical field

Bei der Erfindung wird ausgegangen von einem Verfahren zur Herstellung eines Werkstücks aus einer dotierstoffhaltigen Legierung auf der Basis Titanaluminid.The invention is based on a method for producing a workpiece from a dopant-containing alloy based on titanium aluminide.

Hochtemperaturlegierungen für thermische Maschinen auf der Basis der intermetallischen Verbindung TiAI, welche sich für die Herstellung von gegossenen und geschmiedeten Bauteilen eignen und die konventionellen Nickelbasis-Superlegierungen ergänzen und zum Teil ersetzen können.High-temperature alloys for thermal machines based on the intermetallic compound TiAI, which are suitable for the production of cast and forged components and which can supplement and partially replace the conventional nickel-based superalloys.

Die Erfindung bezieht sich auf das Erschmelzen und Abgiessen von auf der intermetallischen Verbindung TiAI mit weiteren Zusätzen dotierten Legierungen und auf das thermische und thermomechanische Weiterverarbeiten zu brauchbaren Werkstücken mit guten mechanischen Eigenschaften.The invention relates to the melting and casting of alloys doped on the intermetallic compound TiAI with further additives and to the thermal and thermomechanical further processing to usable workpieces with good mechanical properties.

Stand der TechnikState of the art

Intermetallische Verbindungen des Titans mit dem Aluminium haben einige interessante Eigenschaften, welche sie als Konstruktionswerkstoffe im mittleren und höheren Temperaturbereich als attraktiv erscheinen lassen. Dazu gehört unter anderem ihre gegenüber Superlegierungen niedrige Dichte, die nur ca. 1/2 des Wertes für Ni-Superlegierungen erreicht. Ihrer technischen Verwendbarkeit in der vorliegenden Form steht allerdings ihre Sprödigkeit entgegen. Erstere kann durch Zusätze verbessert werden, wobei auch höhere Festigkeitswerte erreicht werden. Als mögliche und zum Teil bereits eingeführte intermetallische Verbindungen sind unter anderem Nickelaluminide, Nickelsilizide und Titanaluminide als Konstruktionsstoffe bekannt.Intermetallic compounds of titanium with aluminum have some interesting properties which make them appear attractive as construction materials in the medium and higher temperature range. Among other things, this includes their low density compared to superalloys, which only reaches about 1/2 of the value for Ni superalloys. Their technical usability in the present form, however, stands in the way of their brittleness. The former can be improved by additives, whereby higher strength values are also achieved. As possible and in part already introduced intermetallic compounds, nickel aluminides, nickel silicides and titanium aluminides are known as construction materials.

Es wurde schon versucht, die Eigenschaften des reinen TiAI durch leichte Veränderungen des Ti/AI-Atomverhältnisses sowie durch Zulegieren von anderen Elementen zu verbessern. Als weitere Elemente wurden beispielsweise alternativ Cr, B, V, Si, Ta sowie (Ni + Si) und (Ni + Si + B) vorgeschlagen, ferner Mn, W, Mo, Nb, Hf. Die Absicht bestand darin, einerseits die Sprödigkeit herabzusetzen, d.h. die Dehnbarkeit und Zähigkeit des Werkstoffs zu erhöhen, andererseits eine möglichst hohe Festigkeit im interessierenden Temperaturbereich zwischen Raumtemperatur und Betriebstemperatur zu erreichen. Ausserdem wurde eine genügend hohe Oxydationsbeständigkeit angestrebt. Diese Ziele wurden jedoch nur teilweise erreicht.Attempts have already been made to improve the properties of the pure TiAl by slightly changing the Ti / Al atomic ratio and by alloying other elements. Cr, B, V, Si, Ta, as well as (Ni + Si) and (Ni + Si + B), as well as Mn, W, Mo, Nb, Hf, were proposed as further elements, for example. The intention was, on the one hand, the brittleness to reduce, ie to increase the ductility and toughness of the material, on the other hand to achieve the highest possible strength in the temperature range of interest between room temperature and operating temperature. A sufficiently high resistance to oxidation was also sought. However, these goals were only partially achieved.

Die Warmfestigkeit der bekannten Aluminide lässt indessen noch zu wünschen übrig. Entsprechend dem vergleichsweise niedrigen Schmelzpunkt dieser Werkstoffe ist die Festigkeit, insbesondere die Kriechfestigkeit im oberen Temperaturbereich ungenügend, wie auch aus diesbezüglichen Veröffentlichungen hervorgeht.However, the heat resistance of the known aluminides still leaves something to be desired. Corresponding to the comparatively low melting point of these materials, the strength, in particular the creep resistance in the upper temperature range, is inadequate, as is also apparent from publications in this regard.

Des weiteren stellt die Formgebung der auf Titanaluminiden basierenden intermetallischen Phasen eine gewisse Problematik dar. Wegen der hohen Affinität der beteiligten Elemente zum Sauerstoff, insbesondere derjenigen des Titans ist die Herstellung von Formteilen durch Giessen erschwert. Schlechtes Formfüllungsvermögen, Porosität und Lunker sind die Folgen. Ausserdem können die Eigenschaften des Gussgefüges durch nachfolgende Wärmebehandlungen nicht im gewünschten Masse verbessert werden. Der klassischen Warmumformung steht andererseits die vergleichsweise mangelhafte Duktilität im unteren Tempeaturbereich entgegen.Furthermore, the shape of the intermetallic phases based on titanium aluminides presents a certain problem. Because of the high affinity of the elements involved for oxygen, in particular that of titanium, the production of molded parts by casting is difficult. Poor mold filling capacity, porosity and cavities are the consequences. In addition, the properties of the cast structure cannot be improved to the desired extent by subsequent heat treatments. On the other hand, classic hot forming is opposed by the comparatively poor ductility in the lower temperature range.

Zum Stand der Technik werden die nachfolgenden Dokumente angegeben:

  • - N.S. Stoloff, "Ordered alloys-physical metallurgy and structural applications", International metals review, Vol. 29, No. 3, 1984, pp. 123-135.
  • - G. Sauthoff, "Intermetallische Phasen", Werkstofe zwischen Metall und Keramik, Magazin neue Werkstoffe 1/89, S. 15-19.
  • - Young-Won Kim, "Intermetallic Alloys based on Gamma Titanium Aluminide", JOM, July 1989.
  • - US-A-4 842 817 US-A-4 842 819 US-A-4 842 820
  • - US-A-4 857 268 US-A-4 836 983 EP-A-0 275 391
The following documents are given regarding the state of the art:
  • - NS Stoloff, "Ordered alloys-physical metallurgy and structural applications", International metals review, vol. 29, no. 3, 1984, pp. 123-135.
  • - G. Sauthoff, "Intermetallic phases", materials between metal and ceramic, magazine new materials 1/89, pp. 15-19.
  • - Young-Won Kim, "Intermetallic Alloys based on Gamma Titanium Aluminide", JOM, July 1989.
  • - US-A-4 842 817 US-A-4 842 819 US-A-4 842 820
  • - US-A-4 857 268 US-A-4 836 983 EP-A-0 275 391

Die Eigenschaften der bekannten modifizierten intermetallischen Verbindungen sowie ihre herkömmlichen Verarbeitungsmethoden genügen den technischen Anforderungen im allgemeinen noch nicht, um daraus brauchbare Werkstücke herzustellen. Dies gilt insbesondere bezüglich Warmfestigkeit und Zähigkeit (Duktilität). Es besteht daher ein Bedürfnis nach Weiterentwicklung und Verbesserung derartiger Werkstoffe und deren Formgebung sowie der günstigen Beeinflussung der mechanischen Eigenschaften der daraus hergestellten Werkstücke.The properties of the known modified intermetallic compounds and their conventional processing methods generally do not yet meet the technical requirements in order to produce usable workpieces from them. This applies in particular to heat resistance and toughness (ductility). There is therefore a need for the further development and improvement of such materials and their shaping, as well as the favorable influence on the mechanical properties of the workpieces made therefrom.

Darstellung der ErfindungPresentation of the invention

Die Erfindung, wie sie in Patentanspruchl angegeben ist, liegt die Aufgabe zugrunde, ein Verfahren zur Herstellung eines Werkstücks aus einer dotierstoffhaltigen Legierung auf der Basis von Titanaluminid anzugeben, welcher zu einem Werkstoff hoher Oxydations- und Korrosionsbeständigkeit, hoher Warmfestigkeit und genügender Duktilität führt.The invention, as specified in claim 1, is based on the object of specifying a method for producing a workpiece from a dopant-containing alloy based on titanium aluminide, which leads to a material having high oxidation and corrosion resistance, high heat resistance and sufficient ductility.

Weg zur Ausführung der ErfindungWay of carrying out the invention

Die Erfindung wird anhand der durch Figuren erläuterten Ausführungsbeispiele beschrieben.The invention is described on the basis of the exemplary embodiments explained by figures.

Dabei zeigt:

  • Fig. 1 ein Fliessbild (Blockdiagramm) des Verfahrens,
  • Fig. 2 ein Fliessbild (Blockdiagramm) einer Variante des Verfahrens.
It shows:
  • 1 is a flow diagram (block diagram) of the method,
  • 2 shows a flow diagram (block diagram) of a variant of the method.

In Fig. 1 ist ein Fliessbild (Blockdiagramm) des Verfahrens dargestellt. Die Figur bedarf keiner weiteren Erklärungen. Der Schwerpunkt der Verfahrensschritte liegt hier auf dem wurden die zylindrischen Blöcke in passende Kapseln aus weichem Kohlenstoffstahl eingeschoben und letztere dicht verschweisst. Die eingekapselten Werkstücke wurden nun bei einer Temperatur von 1260 C während 3 h unter einem Druck von 120 MPa heiss- isostatisch gepresst, abgekühlt, mit 10 bis 50° C/min auf 1100°C erwärmt, gehalten und bei 1100 C isotherm geschmiedet. Das verwendete Werkzeug bestand aus einer Molybdänlegierung mit folgender Zusammensetzung:

  • Ti = 0,5 Gew.-%
  • Zr = 0,1 Gew.-%
  • C = 0,2 Gew.-%
  • Mo = Rest
1 shows a flow diagram (block diagram) of the method. The figure needs no further explanation. The focus of the process steps here is on the cylindrical blocks being inserted into suitable capsules made of soft carbon steel and the latter tightly welded. The encapsulated workpieces were then hot isostatically pressed at a temperature of 1260 C for 3 h under a pressure of 120 MPa, cooled, heated to 1100 ° C at 10 to 50 ° C / min, held and forged at 1100 C isothermally. The tool used consisted of a molybdenum alloy with the following composition:
  • Ti = 0.5% by weight
  • Zr = 0.1% by weight
  • C = 0.2% by weight
  • Mo = rest

Es wurde eine Fliessgrenze des zu schmiedenden Werkstoffs von ca. 260 MPa bei 1100°C festgestellt. Die Umformung bestand in einem Stauchen bis zu einer Verformung ∈ = 1,3, wobei

Figure imgb0001

mit
ho = ursprüngliche Höhe des Werkstücks h = Höhe des Werkstücks nach Umformung bedeuten. Die lineare Verformungsgeschwindigkeit (Stempelgeschwindigkeit der Schmiedepresse) v betrug bei Beginn des Schmiedeprozesses 0,1 mm/s. Die für das Stauchen benötigten Presskräfte waren von mittlerer Grösse. Im vorliegenden Fall betrugen sie ca. 750 kN, was einem Anfangsdruck von ca. 300 MPa entsprach.The yield point of the material to be forged was around 260 MPa at 1100 ° C. The deformation consisted of an upsetting up to a deformation ∈ = 1.3, where
Figure imgb0001
With
h o = original height of the workpiece h = height of the workpiece after forming. The linear rate of deformation (punch speed of the forging press) v was 0.1 mm / s at the start of the forging process. The pressing forces required for the upsetting were of medium size. In the present case, they were approximately 750 kN, which corresponded to an initial pressure of approximately 300 MPa.

Durch dieses Beispiel wurde die ausgezeichnete Umformbarkeit des vorbehandelten Werkstoffs demonstriert, betrug doch die bei Rissfreiheit erreichte Höhenabnahme beim Stauchen über 70 %.This example demonstrated the excellent formability of the pretreated material, as the decrease in height achieved with no cracks during compression was over 70%.

Ausführungsbeispiel 2:Example 2:

Nach der unter Beispiel 1 angegebenen Weise wurde eine Legierung der nachfolgenden Zusammensetzung erschmolzen:

  • AI = 48 At.-%
  • V = 3 At.-%
  • Si = 0,5 At.-%
  • Ti = Rest
An alloy of the following composition was melted in the manner given in Example 1:
  • AI = 48 at .-%
  • V = 3 at .-%
  • Si = 0.5 at .-%
  • Ti = rest

Die Schmelze wurde zu prismatischen Walzbarren von 100 mm x 80 mm x 20 mm abgegossen. Diese wurden zunächst durch Glühen bei ca. 1100° C homogenisiert und deren Gusshaut mechanisch entfernt. Nach Einkapselung und heiss-isostatischem Pressen gemäss Beispiel 1 wurden die Barren bei 1150°C warmgewalzt. Die Höhenabnahme (= Querschnittsabnahme) betrug ca. 40 %. Am gewalzten Halbzeug konnten keinerlei Risse wahrgenommen werden, was für die ausgezeichnete Duktilität des Materials bei dieser Temperatur spricht. Vom gewalzten Stab wurden Abschnitte mit einer Stempelgeschwindigkeit von ca. 0,1 mm/s um einen Betrag, der einem ∈ von 1,2 entsprach, bei 1150°C gestaucht (Höhenabnahme ca. 70 %). Das Schmiedegesenk bestand aus der geringe Ti- und Zr-Mengen enthaltenden Mo-Legierung. Die Fliessgrenze des Werkstücks betrug bei 1150°C ca. 200 MPa. Nach dem Schmieden wies das Werkstück eine Vickershärte HV von durchschnittlich 336 kg/mm2 auf.The melt was poured into prismatic bars of 100 mm x 80 mm x 20 mm. These were first homogenized by annealing at approx. 1100 ° C and the cast skin removed mechanically. After encapsulation and hot isostatic pressing according to Example 1, the bars were hot-rolled at 1150 ° C. The decrease in height (= decrease in cross-section) was approx. 40%. No cracks were noticed on the rolled semi-finished product, which speaks for the excellent ductility of the material at this temperature. Sections of the rolled rod were compressed at a stamp speed of approx. 0.1 mm / s by an amount corresponding to a ∈ of 1.2 at 1150 ° C (decrease in height approx. 70%). The forging die consisted of the Mo alloy containing small amounts of Ti and Zr. The flow limit of the workpiece was approx. 200 MPa at 1150 ° C. After forging, the workpiece had a Vickers hardness HV of an average of 336 kg / mm 2 .

Ausführungsbeispiel 3:Example 3:

Gemäss Beispiel 1 wurde eine Legierung der nachfolgenden Zusammensetzung erschmolzen:

  • AI = 48 At.-%
  • Ge = 3 At.-%
  • Ti = Rest
According to Example 1, an alloy with the following composition was melted:
  • AI = 48 at .-%
  • Ge = 3 at%
  • Ti = rest

Die Schmelze wurde zu Gussblöcken von ca. 55 mm Durchmesser und 65 mm Höhe abgegossen. Hierauf wurden die Gussblöcke unter Argonatmosphäre während 10 h bei einer Temperatur von 1100°C geglüht, abgekühlt und mechanisch bearbeitet zwecks Entfernung der Gusshaut. Durch das Glühen wurde die Legierung homogenisiert. Je nach Legierungszusammensetzung wurde eine geeignete Homogenisierung bei Temperaturen zwischen 1000 und 1150°C und Glühzeiten zwischen einer und dreissig Stunden erreicht. Dann wurden die zylindrischen Werkstücke eingekapselt, heiss- isostatisch gepresst und bei einer Temperatur von 1150°C geschmiedet. Die Verformung ∈ betrug 0,69 (Höhenabnahme 50%), die beobachtete Fliessgrenze ca. 380 MPa. Die Verformungsgeschwindigkeit (Stempelgeschwindigkeit) betrug 0,1 mm/s.The melt was poured into ingots approximately 55 mm in diameter and 65 mm high. The ingots were then annealed in an argon atmosphere for 10 hours at a temperature of 1100 ° C., cooled and mechanically processed to remove the casting skin. The alloy was homogenized by the annealing. Depending on the alloy composition, a suitable homogenization was achieved at temperatures between 1000 and 1150 ° C and annealing times between one and thirty hours. Then the cylindrical workpieces were encapsulated, hot isostatically pressed and forged at a temperature of 1150 ° C. The deformation ∈ was 0.69 (height decrease 50%), the observed yield point was approx. 380 MPa. The rate of deformation (punch speed) was 0.1 mm / s.

Ausführungsbeispiel 4:Example 4:

Es wurde eine Turbinenschaufel aus der nachfolgenden Legierung hergestellt:

  • AI = 48 At.-%
  • Zr = 3 At.-%
  • B = 0,5 At.-%
  • Ti = 48,5 At.-%
A turbine blade was made from the following alloy:
  • AI = 48 at .-%
  • Zr = 3 at .-%
  • B = 0.5 at%
  • Ti = 48.5 at .-%

Zu diesem Zweck wurde zunächst die obige Legierung aus den Elementen erschmolzen und zu einem Block von ca. 90 mm Durchmesser und ca. 250 mm Höhe vergossen. Nach einer Glühoperationen bei 1050° C, Entfernung der Gusshaut, Einkapseln, heiss-isostatisch Pressen etc. wurde der Block zunächst bei 1150°C in der Längsrichtung derart gestaucht, dass er eine Höhenabnahme von ca. 50 % erlitt (E = 0,69). Dabei vergrösserte sich der Durchmesser auf ca. 120 mm. In einem nächsten Schritt wurde der zylindrische Körper in einer ersten Querrichtung derart gestaucht, dass ein ovaler Querschnitt entstand (ca. 30 % Querschnittsabnahme). Dann wurde der ovale Körper in der zweiten, darauf senkrechten Querrichtung um den gleichen Betrag gestaucht. Diese beiden Operationen wurden nach einer Zwischenglühung bei 1200 C während 1 nochmals wiederholt. Nun wurde der derart warmgeknetete Schmiederohling in das Gesenk einer Schmiedepresse eingesetzt, dergestalt, dass die den Fuss bildende Hälfte nur geringen Verformungen ausgesetzt wurde, während die andere, das Schaufelblatt bildende Hälfte in mehreren Operationen mit Zwischenglühen sukzessive über einen ovalen Querschnitt zu einem Tragflügelprofil verformt wurde. Das Schaufelblatt hatte folgende Abmessungen:

  • Breite = 80 mm
  • Dicke = 25 mm
  • Profilhöhe = 30 mm
  • Länge = 200 mm
For this purpose, the above alloy was first melted from the elements and egg Cast a block of approx. 90 mm in diameter and approx. 250 mm in height. After an annealing operation at 1050 ° C, removal of the cast skin, encapsulation, hot isostatic pressing etc., the block was first compressed in the longitudinal direction at 1150 ° C in such a way that it suffered a decrease in height of approx. 50% ( E = 0.69 ). The diameter increased to approx. 120 mm. In a next step, the cylindrical body was compressed in a first transverse direction in such a way that an oval cross section was created (approx. 30% decrease in cross section). Then the oval body was compressed by the same amount in the second transverse direction perpendicular to it. These two operations were repeated after intermediate annealing at 1200 C for 1. Now the hot-kneaded forging blank was inserted into the die of a forging press in such a way that the half forming the foot was only subjected to slight deformations, while the other half, forming the airfoil, was successively deformed in several operations with intermediate annealing to an airfoil profile using an oval cross section . The airfoil had the following dimensions:
  • Width = 80 mm
  • Thickness = 25 mm
  • Profile height = 30 mm
  • Length = 200 mm

Der Schmiedevorgang wurde im wesentlichen isotherm bei einer Temperatur von 1120°C durchgeführt, wobei eine Fliessgrenze von durchschnittlich 250 MPa beobachtet wurde. Die Verformungsgeschwindigkeit (Stempelgeschwindigkeit) zu Beginn jeder Schmiedeoperation betrug ca. 0,1 bis 0,2 mm/s. Nach dem Fertigschmieden des Schaufelblattes wurde der Fussteil noch um ca. 20 % Höhenabnahme in der Längsachse der Schaufel gestaucht. Dann wurde das Werkstück mit einer Geschwindigkeit von 300° C/h auf unter 500° C abgekühlt und nach dem Erkalten während 1 bei einer Temperatur von 800 C angelassen. Damit war die bis auf das Fräsen der Nuten am Tannenbaumfuss Nahezu-Endform der Turbinenschaufel erreicht.The forging process was carried out essentially isothermally at a temperature of 1120 ° C., a flow limit of 250 MPa being observed on average. The rate of deformation (punch speed) at the start of each forging operation was approximately 0.1 to 0.2 mm / s. After the forging of the airfoil was finished, the base part was compressed by a further 20% decrease in height in the longitudinal axis of the airfoil. The workpiece was then cooled to below 500 ° C. at a rate of 300 ° C./h and, after cooling, tempered at 800 ° C. for 1 hour. With this, the almost final shape of the turbine blade was achieved, apart from milling the grooves on the fir tree base.

Ausführungsbeispiel 5:Example 5:

Unter Argonatmosphäre wurde in einem Induktionsofen die nachfolgende Legierung erschmolzen:

  • AI = 48 At.-%
  • Cr = 3 At.-%
  • Ti = 45 At.-%
The following alloy was melted in an induction furnace under an argon atmosphere:
  • AI = 48 at .-%
  • Cr = 3 at .-%
  • Ti = 45 at%

Zunächst wurde ein prismatischer Barren von rechteckigem Querschnitt mit ca. 40 mm Dicke, 90 mm Breite und 250 mm Länge abgegossen. Nach der Wärmebehandlung unter Argonatmosphäre bei einer Temperatur von 1100° C während 10 h wurde die Gusshaut durch Hobeln entfernt und der Barren in weichen Stahl eingekapselt und während 3 h bei 1260°C unter einem Druck von 120 MPa heiss- isostatisch gepresst. Die erste Umformung bestand in einem Stauchen (isotherm Schmieden) in der längeren Querrichtung (hochkant) von ca. 33 %, so dass der Barren einen annähernd quadratischen Querschnitt von ca. 60 mm Seitenlänge annahm. Diese Operation wurde bei einer Temperatur von 1150°C unter Argonatmosphäre durchgeführt. Dann wurde der Barren in der anderen Querrichtung bei der gleichen Temperatur warmgewalzt, wobei er annähernd die ursprüngliche rechteckige Querschnittsform, jedoch mit verminderten Dimensionen annahm. Nach einem Zwischenglühen bei 1200° C während 1 h unter Argonatmosphäre wurde der Barren durch Warmwalzen (40 % Querschnittsabnahme) bei 1050°C zu einem Stab mit Rechteckprofil verformt. Während der Operationen konnte bei 1150° C eine Warmstreckgrenze von ca. 240 MPa beobachtet werden. Das Gefüge des fertigen Stabes war feinkörnig und homogen. Die Vickershärte HV war gegenüber dem Gusszustand um ca. 25 % erhöht.First, a prismatic ingot with a rectangular cross-section was cast with a thickness of approx. 40 mm, 90 mm in width and 250 mm in length. After the heat treatment under an argon atmosphere at a temperature of 1100 ° C. for 10 h, the cast skin was removed by planing and the ingot was encapsulated in soft steel and hot-isostatically pressed at 1260 ° C. for 3 h under a pressure of 120 MPa. The first forming was a compression (isothermal forging) in the longer transverse direction (upright) of approx. 33%, so that the ingot assumed an approximately square cross-section with a side length of approx. 60 mm. This operation was carried out at a temperature of 1150 ° C under an argon atmosphere. Then the ingot was hot rolled in the other transverse direction at the same temperature, taking approximately the original rectangular cross-sectional shape but with reduced dimensions. After intermediate annealing at 1200 ° C for 1 h under an argon atmosphere, the ingot was deformed by hot rolling (40% reduction in cross-section) at 1050 ° C into a rod with a rectangular profile. During the operations, a hot stretch limit of approximately 240 MPa was observed at 1150 ° C. The structure of the finished rod was fine-grained and homogeneous. The Vickers hardness HV was increased by approx. 25% compared to the as-cast state.

Ausführungsbeispiel 6:Example 6:

Es wurde unter Argonatmosphäre im Induktionsofen die nachfolgende Legierung erschmolzen:

  • AI = 48 At.-%
  • W = 3 At.-%
  • Ge = 0,5 At.-%
  • Ti = 48,5 At.-%
The following alloy was melted in an induction furnace under an argon atmosphere:
  • AI = 48 at .-%
  • W = 3 at%
  • Ge = 0.5 at .-%
  • Ti = 48.5 at .-%

Aus der Legierung wurde durch Giessen und Warmumformen eine Turbinenschaufel folgender Abmessungen (Schaufelblatt) hergestellt:

  • Breite = 70 mm
  • Dicke = 21 mm
  • Profilhöhe = 26 mm
  • Länge = 160 mm
A turbine blade of the following dimensions (airfoil) was produced from the alloy by casting and hot forming:
  • Width = 70 mm
  • Thickness = 21 mm
  • Profile height = 26 mm
  • Length = 160 mm

Zunächst wurde ein Körper als abgesetzter Zylinder gegossen. Die totale Höhe betrug 220 mm, die Höhe des kleineren Durchmessers 120 mm, diejenige des grösseren 100 mm, die Durchmesser 60 mm bzw. 100 mm. Der Gussrohling wurde bei 1050°C geglüht, überdreht (Entfernung der Gusshaut) und in eine allseitig abschliessende Hülle aus weichem Stahl eingekapselt und gemäss vorangegangenen Beispielen heissisostatisch gepresst. Dann wurde der Block zunächst mit 30 % Höhenabnahme bei 1150°C in Längsrichtung gestaucht und mehrmals in den Querrichtungen gepresst, derart, dass in der Blattpartie ein ovaler Querschnitt erzeugt wurde. Es wurden Zwischenglühungen bei 1200°C durchgeführt. Der auf diese Weise vorgeschmiedete Rohling mit ovalem Querschnitt in der Blattpartie wurde in das Gesenk einer Schmiedepresse eingelegt und in mehreren Stufen bis zum Erreichen des obigen Blattprofils verformt. Der Schmiedeprozess wurde im wesentlichen isotherm bei einer Temperatur von 1150°C durchgeführt. Es wurde eine Fliessgrenze von durchschnittlich 200 MPa bei dieser Temperatur beobachtet. Die Verformugnsgeschwindigkeit (Stempelgeschwindigkeit) zu Beginn der Gesenkschmiedeoperationen betrug ca. 0,2 mm/s. Die übrigen Verfahrensschritte waren analog zu Beispiel 4. Das Anlassen wurde bei einer Temperatur von 750 C während 2h durchgeführt. Das Gefüge der fertigen Turbinenschaufel war feinkörnig und homogen. Die Vickershärte HV war gegenüber dem Gusszustand um 15 % höher.First, a body was cast as a stepped cylinder. The total height was 220 mm, the height of the smaller diameter 120 mm, that of the larger 100 mm, the diameters 60 mm and 100 mm. The cast blank was annealed at 1050 ° C, overturned (removal of the cast skin) and encapsulated in an all-round sleeve made of soft steel and hot isostatically pressed according to the previous examples. Then the block was first compressed in the longitudinal direction with a 30% decrease in height at 1150 ° C. and pressed several times in the transverse directions in such a way that an oval cross section was produced in the leaf section. Intermediate annealing was carried out at 1200 ° C. The pre-forged blank with an oval cross-section in the sheet section was placed in the die of a forging press and in several stages up to Deformed reaching the above leaf profile. The forging process was carried out essentially isothermally at a temperature of 1150 ° C. A flow limit of 200 MPa on average was observed at this temperature. The rate of deformation (punch speed) at the start of the drop forging operations was approximately 0.2 mm / s. The remaining process steps were analogous to Example 4. The tempering was carried out at a temperature of 750 ° C. for 2 hours. The structure of the finished turbine blade was fine-grained and homogeneous. The Vickers hardness HV was 15% higher than the as-cast state.

Es wurden noch zahlreiche andere Schmelzen mit den Legierungselementen Co, Pd, Mo, Mn, Ta, Nb, Hf untersucht und deren Umformbarkeit geprüft. Die Umformbedingungen waren im wesentlichen die gleichen wie in den Ausführungsbeispielen angegeben. Die günstigsten Umformungstemperaturen lagen im Bereich von 1100 bis 1150°C. Die dabei beobachteten Warmfliessgrenzen bewegten sich zwischen den Werten 180 MPa und 260 MPa. Die optimalen Verformungsgeschwindigkeiten (Stempelgeschwindigkeiten) der Schmiedepresse lagen zwischen ca. 0,05 mm/s und 0,2 mm/s, entsprechend Werten für ∈ zwischen 10-4s-1und 10-2 S-1.Numerous other melts with the alloying elements Co, Pd, Mo, Mn, Ta, Nb, Hf were examined and their formability was checked. The forming conditions were essentially the same as specified in the working examples. The most favorable forming temperatures were in the range from 1100 to 1150 ° C. The observed hot flow limits were between 180 MPa and 260 MPa. The optimal deformation speeds (punch speeds) of the forging press were between approx. 0.05 mm / s and 0.2 mm / s, corresponding to values for ∈ between 10 -4 s -1 and 10- 2 S - 1 .

Wirkung der Elemente:Effect of the elements:

Durch Zulegieren der Elemente W, Cr, Mn und Nb einzeln oder in Kombination zu einer Ti/AI-Grundlegierung wird in allen Fällen eine Härte- und Festigkeitssteigerung erzielt. Dabei ist die Wirkung von Kombinationen (z.B. Mn + Nb) am stärksten. Im allgemeinen ist die Härtesteigerung mit einer mehr oder weniger starken Einbusse an Dehnbarkeit verbunden, die aber durch Zulegieren von weiteren Elementen, die zähigkeitserhöhend wirken, wenigstens zum Teil wieder wettgemacht werden können.By adding the elements W, Cr, Mn and Nb individually or in combination to a Ti / Al base alloy, an increase in hardness and strength is achieved in all cases. The effect of combinations (e.g. Mn + Nb) is strongest. In general, the increase in hardness is associated with a more or less severe loss of ductility, which can, however, be at least partially compensated for by adding further elements which increase the toughness.

Eine Zugabe von weniger als 0,5 At.-% eines Elements ist meist kaum wirksam. Andererseits zeigt sich bei ca. 3 - 4 At.-% eine gewisse Sättigungserscheinung, so dass weitere Zugaben sinnlos sind oder die Eigenschaften des Werkstoffs insgesamt wieder verschlechtern.The addition of less than 0.5 at.% Of an element is usually hardly effective. On the other hand, there is a certain saturation phenomenon at approx. 3 - 4 at%, so that further additions are pointless or the properties of the material as a whole deteriorate again.

B wirkt im allgemeinen stark zähigkeitserhöhend im Verein mit anderen, die Festigkeit erhöhenden Elementen. Hier konnte der durch Zulegieren von W verursachte Verlust an Dehnbarkeit durch eine Zugabe von nur 0,5 At.-% B praktisch wettgemacht werden. Höhere Zugaben als 1 At.-% B sind nicht notwendig.B generally has a strong toughness-increasing effect in combination with other strength-increasing elements. Here the loss of ductility caused by alloying W could be practically compensated for by adding only 0.5 at.% B. Additions higher than 1 at.% B are not necessary.

Zur weiteren Optimierung der Eigenschaften bieten sich polynäre Systeme an, bei denen versucht wird, die negativen Eigenschaften von Einzelzugaben durch gleichzeitiges Zulegieren anderer Elemente wieder wettzumachen.For further optimization of the properties, there are polynary systems in which an attempt is made to make up for the negative properties of individual additions by simultaneously alloying other elements.

Der Einsatzbereich der modifizierten Titanaluminide erstreckt sich vorteilhafterweise auf Temperaturen zwischen 600 und 1000 C.The area of application of the modified titanium aluminides advantageously extends to temperatures between 600 and 1000 C.

Die Erfindung ist nicht auf die Ausführungsbeispiele beschränkt.The invention is not restricted to the exemplary embodiments.

Ganz allgemein ist das Verfahren zur Herstellung eines Werkstücks aus einer dotierstoffhaltigen intermetallischen Verbindung des Typs Titanaluminid TiAI durch Wärmebehandeln und Warmumformen dadurch gekennzeichnet, dass folgende Verfahrensschritten durchgeführt werden:

  • - Erschmelzen der Legierung,
  • - Vergiessen der Schmelze zu einem Gusskörper,
  • - Abkühlen des Gusskörpers auf Raumtemperatur und Entfernen seiner Gusshaut und seiner Zunderschicht,
  • - Heiss-isostatisches Pressen des entzunderten Gusskörpers bei einer Temperatur zwischen 1200 und 1300 C und einem Druck zwischen 100 und 150 MPa,
  • - Abkühlen des heiss-isostatisch gepressten Gusskörpers,
  • - Erwärmen des abgekühlten Gusskörpers auf Temperaturen von 1050 bis 1200 C,
  • - Ein- bis mehrmaliges Verformen bei dieser Temperatur zwecks Formgebung und Gefügeverbesserung,
  • - Abkühlen des verformten Gusskörpers auf Raumtemperatur und
  • - Materialabhebendes Bearbeiten des verformten Gusskörpers zum Werkstück.
In general, the process for producing a workpiece from a dopant-containing intermetallic compound of the titanium aluminide TiAI type by heat treatment and hot forming is characterized in that the following process steps are carried out:
  • Melting the alloy,
  • - pouring the melt into a cast body,
  • Cooling the cast body to room temperature and removing its cast skin and scale layer,
  • Hot isostatic pressing of the descaled cast body at a temperature between 1200 and 1300 C and a pressure between 100 and 150 MPa,
  • Cooling the hot isostatically pressed cast body,
  • - heating the cooled cast body to temperatures of 1050 to 1200 C,
  • - One or more deformations at this temperature in order to shape and improve the structure,
  • - Cooling the deformed cast body to room temperature and
  • - Material-lifting processing of the deformed cast body to the workpiece.

In vorteilhafter Weise wird die Warmverformung wie folgt durchgeführt:

  • - Isothermes Verformen des Ganzen im Temperaturbereich zwischen 1050 und 1150 C mit einer Verformungsgeschwindigkeit ∈ = 5
  • · 10-5s-1 bis 10-2s-1 bis zu einer Verformung ∈ = 1,6, wobei
    Figure imgb0002
    ho = ursprüngliche Höhe des Werkstücks, h = Höhe des Werkstücks nach Umformung bedeuten.
The thermoforming is advantageously carried out as follows:
  • - Isothermal deformation of the whole in the temperature range between 1050 and 1150 C with a deformation rate ∈ = 5
  • · 10 -5 s -1 to 10 -2 s -1 up to a deformation ∈ = 1.6, whereby
    Figure imgb0002
    h o = original height of the workpiece, h = height of the workpiece after forming.

Vorzugsweise geschieht diese Verformung wie folgt:

  • - Stauchen in Längsrichtung um 50% Höhenabnahme,
  • - Stauchen in erster Querrichtung um 30% Querschnittsabnahme,
  • - Stauchen in zweiter Querrichtung um 30% Querschnittsabnahme,
  • - Stauchen in Längsrichtung um 20% Höhenabnahme
  • - Abkühlen mit 300 C/h auf unter 500 C,
  • - Anlassen auf 800 C während 1 h,
  • - Abkühlen auf Raumtemperatur.
This deformation preferably takes place as follows:
  • - compression in the longitudinal direction by 50% decrease in height,
  • - compression in the first transverse direction by 30% reduction in cross-section,
  • - compression in the second transverse direction by 30% reduction in cross-section,
  • - Compression in the longitudinal direction by 20% heights decrease
  • Cooling at 300 C / h to below 500 C,
  • - tempering at 800 C for 1 h,
  • - cooling to room temperature.

In einer speziellen Ausführungsform wird das Werkstück im wesentlichen isotherm geschmiedet, wobei es nach dem isothermen Schmieden die Form einer Gasturbinenschaufel aufweist. Zur Herstellung von Halbzeug wird das Werkstück im wesentlichen isotherm geschmiedet und nach dem isothermen Schmieden einem weiteren Warmverformungsprozess mit bis 40% Querschnittsabnahme unterworfen, wobei letzterer vorteilhafterweise in einem Warmwalzen besteht.In a special embodiment, the workpiece is essentially forged isothermally, and after the isothermal forging it has the shape of a gas turbine blade. To produce semifinished products, the workpiece is essentially forged isothermally and, after the isothermal forging, is subjected to a further hot-forming process with up to 40% reduction in cross-section, the latter advantageously consisting of hot rolling.

Das Verfahren wird durchgeführt an Legierungen, welche die nachstehende Zusammensetzung haben:

  • a). AI = 48 At.-%
  • Zr = 3 At.-%
  • B = 0,5 At.-%
  • Ti = 48,5 At.-%
  • b). AI = 48 At.-%
  • V = 3 At.-%
  • Si = 0,5 At.-%
  • Ti = 48,5 At.-%
  • c). AI = 48 At.-%
  • Cr = 3 At.-%
  • Ti = 49 At.-%
  • d). AI = 48 At.-%
  • Y = 3 At.-%
  • B = 0,5 At.-%
  • Ti = 48,5 At.-%
  • e). AI = 48 At.-%
  • Ge = 3 At.-%
  • Ti = 49 At.-%
  • f). AI = 48 At.-%
  • W = 3 At.-%
  • Ge = 0,5 At.-%
  • Ti = 48,5 At.-%
The process is carried out on alloys which have the following composition:
  • a). AI = 48 at .-%
  • Zr = 3 at .-%
  • B = 0.5 at%
  • Ti = 48.5 at .-%
  • b). AI = 48 at .-%
  • V = 3 at .-%
  • Si = 0.5 at .-%
  • Ti = 48.5 at .-%
  • c). AI = 48 at .-%
  • Cr = 3 at .-%
  • Ti = 49 at%
  • d). AI = 48 at .-%
  • Y = 3 at .-%
  • B = 0.5 at%
  • Ti = 48.5 at .-%
  • e). AI = 48 at .-%
  • Ge = 3 at%
  • Ti = 49 at%
  • f). AI = 48 at .-%
  • W = 3 at%
  • Ge = 0.5 at .-%
  • Ti = 48.5 at .-%

Claims (8)

1. Verfahren zur Herstellung eines Werkstücks aus einer dotierstoffhaltigen Legierung auf der Basis Titanaluminid, dadurch gekennzeichnet, dass folgende Verfahrensschritten durchgeführt werden: - Erschmelzen der Legierung, - Vergiessen der Schmelze zu einem Gusskörper, - Abkühlen des Gusskörpers auf Raumtemperatur und Entfernen seiner Gusshaut und seiner Zunderschicht, - Heiss-isostatisches Pressen des entzunderten Gusskörpers bei einer Temperatur zwischen 1200 und 1300°C und einem Druck zwischen 100 und 150 MPa, - Abkühlen des heiss-isostatisch gepressten Gusskörpers, - Erwärmen des abgekühlten Gusskörpers auf Temperaturen von 1050 bis 1200° C, - Ein- bis mehrmaliges Verformen bei dieser Temperatur zwecks Formgebung und Gefügeverbesserung, - Abkühlen des verformten Gusskörpers auf Raumtemperatur und - Materialabhebendes Bearbeiten des verformten Gusskörpers zum Werkstück. 1. A process for producing a workpiece from a dopant-containing alloy based on titanium aluminide, characterized in that the following process steps are carried out: Melting the alloy, - pouring the melt into a cast body, Cooling the cast body to room temperature and removing its cast skin and scale layer, - hot isostatic pressing of the descaled cast body at a temperature between 1200 and 1300 ° C and a pressure between 100 and 150 MPa, Cooling the hot isostatically pressed cast body, - heating the cooled cast body to temperatures from 1050 to 1200 ° C, - One or more deformations at this temperature in order to shape and improve the structure, - Cooling the deformed cast body to room temperature and - Material-lifting processing of the deformed cast body to the workpiece. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass eine mit mindestens einem der Elemente Zr, V, Cr, Si, Y, W, B, Ge dotierte TiAI-Legierung den folgenden zusätzlichen Verfahrensschritten unterworfen wird: - Schmelzen der Legierung im Vakuum-oder Schutzgas-Induktionsofen, - Glühen unter Schutzgas oder Vakuum bei einer Temperatur zwischen 1000 und 1150°C, - Einsetzen des Gusskörpers nach dem Entfernen der Gusshaut und der Zunderschicht in eine weiche Stahlkapsel und luftdichtes Verschliessen der gefüllten Stahlkapsel, - Heiss-isostatisches Pressen der den Gusskörper aufnehmenden, verschlossenen Stahlkapsel, - Erwärmen mit 10 - 50°C/min auf 1050 bis 1150°C, - Halten auf dieser Temperatur während 5 bis 20 min. 2. The method according to claim 1, characterized in that a TiAI alloy doped with at least one of the elements Zr, V, Cr, Si, Y, W, B, Ge is subjected to the following additional process steps: Melting the alloy in a vacuum or inert gas induction furnace, - annealing under protective gas or vacuum at a temperature between 1000 and 1150 ° C, - inserting the cast body after removing the cast skin and the scale layer in a soft steel capsule and hermetically sealing the filled steel capsule, - hot isostatic pressing of the sealed steel capsule receiving the cast body, - heating at 10 - 50 ° C / min to 1050 to 1150 ° C, - Hold at this temperature for 5 to 20 minutes. 3. Verfahren nach einem der Ansprüche 1 oder 2, dadurch gekennzeichnet, dass die Warmverformung wie folgt durchgeführt wird: - Isothermes Verformen des Ganzen im Temperaturbereich zwischen 1050 und 1150°C mit einer Verformungsgeschwindigkeit ∈= 5 · 10-5s-1 bis 10-2s-1 bis zu einer Verformung ∈ = 1,6, wobei
Figure imgb0003
ho = ursprüngliche Höhe des Werkstücks, h = Höhe des Werkstücks nach Umformung bedeuten. 3. The method according to any one of claims 1 or 2, characterized in that the hot forming is carried out as follows: - Isothermal deformation of the whole in the temperature range between 1050 and 1150 ° C with a deformation rate ∈ = 5 · 10 -5 s -1 to 10 -2 s -1 up to a deformation ∈ = 1.6, whereby
Figure imgb0003
 h o = original height of the workpiece, h = height of the workpiece after forming. 4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass die Warmverformung wie folgt durchgeführt wird: - Stauchen in Längsrichtung um 50% Höhenabnahme, - Stauchen in erster Querrichtung um 30% Querschnittsabnahme, - Stauchen in zweiter Querrichtung um 30% Querschnittsabnahme, - Stauchen in Längsrichtung um 20% Höhenabnahme, - Abkühlen mit 300 C/h auf unter 500° C, - Anlassen auf 800° C während 1 h, - Abkühlen auf Raumtemperatur. 4. The method according to any one of claims 1 to 3, characterized in that the hot forming is carried out as follows: - compression in the longitudinal direction by 50% decrease in height, - compression in the first transverse direction by 30% reduction in cross-section, - compression in the second transverse direction by 30% reduction in cross-section, - compression in the longitudinal direction by 20% decrease in height, Cooling at 300 C / h to below 500 ° C, - tempering at 800 ° C for 1 h, - cooling to room temperature. 5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass das Werkstück im wesentlichen isotherm geschmiedet wird und nach dem isothermen Schmieden die Form einer Gasturbinenschaufel hat.5. The method according to any one of claims 1 to 4, characterized in that the workpiece is forged essentially isothermally and has the shape of a gas turbine blade after the isothermal forging. 6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass das Werkstück im wesentlichen isotherm geschmiedet wird und nach dem isothermen Schmieden einem weiteren Warmverformungsprozess mit bis 40% Querschnittsabnahme unterworfen wird.6. The method according to any one of claims 1 to 5, characterized in that the workpiece is forged essentially isothermally and after the isothermal forging is subjected to a further hot deformation process with up to 40% decrease in cross-section. 7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, dass der Warmverformungsprozess in einem Warmwalzen besteht.7. The method according to claim 6, characterized in that the hot forming process consists in hot rolling. 8. Verfahren nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass die Legierung eine der nachstehende Zusammensetzungen aufweist: AI = 48 At.-% Zr = 3 At.-% B = 0,5 At.-% Ti = 48,5 At.-% oder AI = 48 At.-% V = 3 At.-% Si = 0,5 At.-% Ti = 48,5 At.-% oder AI = 48 At.-% Cr = 3 At.-% Ti = 49 At.-% oder AI = 48 At.-% Y = 3 At.-% B = 0,5 At.-% Ti = 48,5 At.-% oder AI = 48 At.-% Ge = 3 At.-% Ti = 49 At.-% oder AI = 48 At.-% W = 3 At.-% Ge = 0,5 At.-% Ti = 48,5 At.-% 8. The method according to any one of claims 1 to 7, characterized in that the alloy has one of the following compositions: AI = 48 at .-% Zr = 3 at .-% B = 0.5 at% Ti = 48.5 at .-% or AI = 48 at .-% V = 3 at .-% Si = 0.5 at .-% Ti = 48.5 at .-% or AI = 48 at .-% Cr = 3 at .-% Ti = 49 at% or AI = 48 at .-% Y = 3 at .-% B = 0.5 at% Ti = 48.5 at .-% or AI = 48 at .-% Ge = 3 at% Ti = 49 at% or AI = 48 at .-% W = 3 at% Ge = 0.5 at .-% Ti = 48.5 at .-%
EP91108605A 1990-07-04 1991-05-27 Process for producing a work piece from an alloy based on titanium aluminide containing a doping material Expired - Lifetime EP0464366B1 (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
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EP0549181A1 (en) * 1991-12-23 1993-06-30 General Electric Company Gamma titanium aluminide
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