EP2393952B1 - Method for the beta annealing of a workpiece produced from a ti alloy - Google Patents

Method for the beta annealing of a workpiece produced from a ti alloy Download PDF

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Publication number
EP2393952B1
EP2393952B1 EP10702655.1A EP10702655A EP2393952B1 EP 2393952 B1 EP2393952 B1 EP 2393952B1 EP 10702655 A EP10702655 A EP 10702655A EP 2393952 B1 EP2393952 B1 EP 2393952B1
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temperature
workpiece
holding
annealing
furnace
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German (de)
French (fr)
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EP2393952A1 (en
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Markus BÜSCHER
Thomas Witulski
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Otto Fuchs KG
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Otto Fuchs KG
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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

Definitions

  • the invention relates to a method for heat treating a workpiece made of a titanium alloy for adjusting a fine-grained structure by annealing the workpiece above its ⁇ -transus temperature ( ⁇ -annealing), wherein the workpiece is heated in an oven to a temperature level above its ⁇ -transus temperature and the achievement of the temperature level is determined the beginning of a predefined with respect to its duration holding time and the workpiece is left for the duration of the holding time at the temperature level before it is subjected to a cooling process.
  • ⁇ -annealing ⁇ -transus temperature
  • Titanium alloy workpieces are subjected to different heat treatments depending on their chemistry and purpose, to impart certain properties to the workpiece. Titanium alloy workpieces are sometimes subjected to an annealing process for this purpose.
  • the main application of such annealing processes depending on the type of alloy and the respective desired property to be achieved, is an increase in strength, the setting of sufficient toughness and thermal stability and / or an increase in creep resistance.
  • One of these heat treatment methods is the so-called ⁇ -annealing.
  • the workpiece is annealed just above its ⁇ -transformation temperature ( ⁇ -transus temperature) and then subjected to a defined cooling process, which may be a cooling in air or an inert gas to room temperature or quenching.
  • the hexagonal ⁇ -phase contained in the Ti alloy is converted into a body-centered ⁇ -phase.
  • the quenching process subsequent to the ⁇ -annealing is typically designed to suppress or specifically precipitate the formation of ⁇ -phase during cooling.
  • Workpieces made of Ti alloys may be structural components, for example for use in aircraft construction. Such structural components typically have a not inconsiderable thickness. When ⁇ -annealing such a workpiece special care is required to achieve the desired properties. For this purpose, standards have been developed according to which specifications such Ti structural components must be annealed. By standardizing the ⁇ -annealing process, it is intended to ensure that in an industrial application of the ⁇ -annealing process, the workpieces have as uniform a grain structure as possible. The problem with ⁇ -annealing is that too long holding of the workpiece above its ⁇ -transus temperature leads to undesired grain coarsening.
  • the workpiece is heated to a temperature which is 30 ° C above the ⁇ -transus temperature of the Ti alloy.
  • the temperature level above the ⁇ -transus temperature, to which the workpiece is to be heated has a sufficient temperature difference to the ⁇ -transus temperature, which is also ensured taking into account the system-related temperature tolerances ( ⁇ -transus temperature, furnace temperature) that the workpiece as a whole Reaching the temperature level is heated above the ⁇ -transus temperature.
  • the set oven temperature a tolerance range of ⁇ 14 ° C is usually specified. A ⁇ -anneal is performed according to these specifications by heating the workpiece in an oven.
  • the workpiece temperature exceeds the lower tolerance limit of the predefined temperature level (T ⁇ + 30 ° C-14 ° C)
  • T ⁇ + 30 ° C-14 ° C the time at which the holding time begins.
  • the holding time itself is given as 30 minutes, for example. Accordingly, the workpiece is left in the oven for the duration of the holding time at a temperature level above T ⁇ + 30 ° -14 ° C and then subjected to a cooling process.
  • Such a method is in principle GB 1,141,409 known. Described in this document is a method of grain refining the microstructure of an ⁇ - or ⁇ - ⁇ -titanium alloy.
  • the workpiece is heated to a temperature above the ⁇ -transus temperature to obtain substantially complete conversion to the ⁇ -phase. At this temperature, the workpiece is held until it is sufficiently certain that complete conversion to the ⁇ phase has occurred. As an example, a hold time of one hour is given. Subsequently, the workpiece is quenched to a temperature sufficiently low below the ⁇ -transus temperature to bring a substantial portion of the ⁇ -phase into an ⁇ -phase or an ⁇ -equivalent phase. In a subsequent step, the fitting is plastically deformed.
  • Annealing in this document refers to an intermediate step in the preparation of an annealed material having a globular ⁇ -phase microstructure that is adjusted after ⁇ -annealing and after further deformation. This document does not describe a ⁇ -anneal, which is a final heat treatment, which refines the grain size of the ⁇ -structure, as this entry is mentioned.
  • the invention is therefore the object of an initially mentioned method in such a way that a ⁇ -annealing of workpieces made of a titanium alloy with a higher degree of process reliability is possible.
  • the oven temperature should be set just above the ⁇ -transus temperature to avoid grain coarsening due to too high a temperature
  • the oven is set at a temperature above that temperature level at which Exceeding the hold time begins to run. Exploited in this process the property that within the observed temperature window above the ⁇ -transus temperature, the temperature has only a minor influence on the grain growth. Decisive for the grain growth and the grain size of the ⁇ -annealed workpiece is rather the holding time.
  • the oven temperature By setting the oven temperature to a temperature significantly different from the temperature at which the hold period begins, the time between when the workpiece exceeds its ⁇ -transus temperature and reaching the onset of holding time is achieved determining temperature levels compared to a conventional ⁇ -annealing as a result of the faster heating of the workpiece by the inventively set higher furnace temperature is considerably shorter.
  • the heating behavior of a Ti workpiece, whose heating gradient decreases with increasing temperature, is also utilized in this method.
  • the portion of the heating curve of the workpiece between its ⁇ -transus temperature and the temperature level of the holding time is in a portion of the heating curve having a higher gradient compared to the conventional ⁇ -annealing process.
  • the oven set temperature will be adjusted depending on the Ti alloy and the geometry of the workpiece. It is considered sufficient if the Ofeneinstelltemperatur is 50 ° C above the ⁇ transus temperature and thus well above the provided for holding temperature levels of T ⁇ + 30 ° C-14 ° C. For economic reasons, the oven setting temperature will not be set too high.
  • the maximum oven setting temperature will depend on the temperature Select grain size growth and the intended holding time and the expected time required for heating the workpiece from its ⁇ -transus temperature to the temperature level of the holding time. Tests have shown that even a Ofeneinstelltemperatur of T ⁇ + 100 ° C leads to the expected results, without having to accept conditionally by the increasing warming during the holding time, a too large grain growth.
  • the time for heating the workpiece from its ⁇ -transus temperature to the temperature level of the hold time is correspondingly short.
  • a furnace setting temperature for heating the workpiece which, as described in the above example, is considerably above the ⁇ -transus temperature, it is possible, after reaching the holding temperature, the furnace temperature a temperature which is only a little above the ⁇ -temperature is lower. This in turn reduces temperature-induced grain growth.
  • the claimed method is proposed for the first time to use the furnace temperature as a manipulated variable to not insignificantly improve the process of a ⁇ -annealing of a workpiece made of a Ti alloy, in particular to be able to produce the workpieces produced by this heat treatment process with respect to in the desired property , It may well be provided to use the furnace temperature as an active manipulated variable, which, after the workpiece has reached a predetermined temperature, is lowered by a first set temperature.
  • FIG. 1 In the diagram of FIG. 1 is the inventive ⁇ -annealing of a workpiece made of a Ti alloy based on a temperature / time diagram shown. Entered in the diagram is the heating curve A of a Ti workpiece, which is made in the illustrated embodiment of a Ti6A14V alloy.
  • the chemistry of a Ti6A14V alloy is shown below: al V Fe O C N H Y Others, individually Others, sum Ti 5.5 to 6.75 3.5-4.5 Max. 0.30 Max. 0.20 Max. 0.08 Max. 0.05 Max. 0.0125 Max. 0.005 0.10 0.40 rest
  • the ⁇ -transus temperature T ⁇ of the Ti alloy used for this workpiece is about 970 ° C.
  • the furnace in which the workpiece is to be subjected to the ⁇ -annealing process is set in the illustrated embodiment to a temperature of T ⁇ + 50 ° C.
  • the furnace setting temperature T F is 1,020 ° C.
  • the ⁇ -transus temperature T ⁇ and the set furnace temperature T F as a solid line, the tolerance range of the two temperatures T ⁇ and T F rasterized above and below the respective temperature T ⁇ and T F is entered. Also entered is the lower limit of the temperature level T H determined for holding the workpiece for the ⁇ -annealing process.
  • the time of reaching the workpiece of the temperature T H determines the beginning of the holding time - the time that the workpiece for normal execution of the ⁇ -annealing on or above the temperature T H is to be left.
  • the lower limit of the temperature level for the holding time is the temperature that defines the start of the holding time also in conventional methods, namely T ⁇ + 30 ° C-14 ° C for the Ti6A14V alloy in question.
  • the heating of the Ti workpiece can be done from a cold oven or in an already preheated oven.
  • the heating curve A is determined by a starting from a certain temperature increasingly decreasing heating gradient. The smaller the temperature difference between the current temperature of the workpiece and the furnace setting temperature T F , the lower the heating gradient.
  • the temperature of the workpiece at the time t 1 exceeds the upper limit of the tolerance of the ⁇ -transus temperature T ⁇ .
  • the lower limit of the temperature level T H is above the upper limit of the tolerance range of the ⁇ -transus temperature T ⁇ .
  • the holding time which is predefined with regard to its duration, which is selected as 30 minutes in the present exemplary embodiment, begins.
  • the holding time is entered at time t 3 .
  • the workpiece is removed from the oven and subjected to a defined cooling process.
  • the heating curve A, the time interval between the times t 1 , t 2 is about 15 - 20 minutes.
  • the furnace can be lowered to a lower temperature level. This reduces the energy consumption and, albeit slight influence of the temperature on the grain growth above the ⁇ -transus temperature. This happens at time t 2 or shortly thereafter.
  • the furnace temperature can be lowered to the temperature intended for holding, which in the exemplary embodiment illustrated is T ⁇ + 30 ° C.-14 ° C.
  • FIG. 1 The ⁇ -anneal described above is in FIG. 1 contrasting the conventional ⁇ -annealing of a Ti workpiece.
  • This Ti workpiece has the same alloy composition as that which has been heat-treated with the ⁇ -annealing of the present invention.
  • T F ' the tolerance range above and below is indicated by a screening. Due to the lower Ofeneinstelltemperatur T F ', compared with the embodiment according to the invention, the heating process of the workpiece, in FIG. 1 shown dash-dotted on the basis of its warm-up curve A ', overall slower.
  • the upper limit of the tolerance range of the ⁇ -transus temperature is exceeded and at time t 2 ' the lower limit of the temperature level T H of the holding time. If the temperature level T H is exceeded at time t 2 ', the 30-minute hold time begins.
  • the shorter time interval in the inventive method between the time of reaching the ⁇ -transus temperature or the lower limit of the tolerance range thereof and the achievement of the temperature T H not only explains the higher process reliability of this method but also that the ⁇ -annealed workpiece with this method overall fine-grained and has a more homogeneous particle size distribution.
  • a particle size analysis was carried out on the two workpieces.
  • an average grain size of 0.74 mm has been achieved.
  • the ⁇ -annealed sample according to the invention had an average grain size of only 0.58 mm.
  • the deviation of the grain sizes from the aforementioned mean value is smaller in the case of the ⁇ -annealed sample according to the invention than in the case of that which has been subjected to conventional ⁇ -annealing.
  • FIG. 2 shows a grain size comparison diagram in which, depending on the holding time of the Ti6Al4V alloy used for the annealing experiments, the grain size is plotted. Registered in the diagram are four curves differing in the temperature of their holding time. The four samples had the following alloy composition: al V Fe O C N H Y Others, individually Others, sum Ti 5.92 3.82 0.18 0.11 0,006 0.005 0.0035 ⁇ 0.005 ⁇ 0.10 ⁇ 0.30 rest

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Description

Die Erfindung betrifft ein Verfahren zum Wärmebehandeln eines aus einer Titanlegierung hergestellten Werkstückes zum Einstellen eines feinkörnigen Gefüges durch Glühen des Werkstückes oberhalb seiner β-Transus-temperatur (β-Glühen), wobei das Werkstück in einem Ofen auf ein Temperaturniveau oberhalb seiner β-Transustemperatur erwärmt wird und das Erreichen des Temperaturniveaus den Beginn einer bezüglich seiner Dauer vordefinierten Haltezeit bestimmt und das Werkstück für die Dauer der Haltezeit auf dem Temperaturniveau belassen wird, bevor es einem Abkühlprozess unterworfen wird.The invention relates to a method for heat treating a workpiece made of a titanium alloy for adjusting a fine-grained structure by annealing the workpiece above its β-transus temperature (β-annealing), wherein the workpiece is heated in an oven to a temperature level above its β-transus temperature and the achievement of the temperature level is determined the beginning of a predefined with respect to its duration holding time and the workpiece is left for the duration of the holding time at the temperature level before it is subjected to a cooling process.

Werkstücke, die aus einer Titanlegierung bestehen, werden in Abhängigkeit von ihrem Chemismus und ihrem Einsatzzweck unterschiedlichen Wärmebehandlungen unterworfen, um dem Werkstück bestimmte Eigenschaften zu verleihen bzw. einzustellen. Werkstücke aus Titanlegierungen werden zu diesem Zwecke mitunter einem Glühverfahren unterworfen. Hauptanwendungszweck derartiger Glühverfahren liegt je nach Legierungstyp und der jeweils gewünschten zu erreichenden Eigenschaft in einer Steigerung der Festigkeit, dem Einstellen einer hinreichenden Zähigkeit sowie einer thermischen Stabilität und/oder zur Erhöhung der Kriechbeständigkeit. Eines dieser Warmbehandlungsverfahren ist das sogenannte β-Glühen. Bei diesem Verfahren wird das Werkstück knapp oberhalb seiner β-Umwandlungstemperatur (β-Transustemperatur) geglüht und anschließend einem definierten Abkühlprozess unterworfen, wobei es sich hierbei um ein Abkühlen in Luft oder einem inerten Gas auf Raumtemperatur oder auch um ein Abschrecken handeln kann. Oberhalb der β-Transus-temperatur wird die in der Ti-Legierung enthaltene hexagonale α-Phase in eine raumzentrierte β-Phase umgewandelt. Der sich an das β-Glühen anschließende Abschreckprozess ist typischerweise ausgelegt, um bei der Abkühlung die Ausbildung von α-Phase möglichst zu unterdrücken oder definiert auszuscheiden.Workpieces consisting of a titanium alloy are subjected to different heat treatments depending on their chemistry and purpose, to impart certain properties to the workpiece. Titanium alloy workpieces are sometimes subjected to an annealing process for this purpose. The main application of such annealing processes, depending on the type of alloy and the respective desired property to be achieved, is an increase in strength, the setting of sufficient toughness and thermal stability and / or an increase in creep resistance. One of these heat treatment methods is the so-called β-annealing. In this method, the workpiece is annealed just above its β-transformation temperature (β-transus temperature) and then subjected to a defined cooling process, which may be a cooling in air or an inert gas to room temperature or quenching. Above the β-transus temperature, the hexagonal α-phase contained in the Ti alloy is converted into a body-centered β-phase. The quenching process subsequent to the β-annealing is typically designed to suppress or specifically precipitate the formation of α-phase during cooling.

Bei Werkstücken aus Ti-Legierungen kann es sich um Strukturbauteile, etwa zur Verwendung im Flugzeugbau, handeln. Derartige Strukturbauteile weisen typischerweise eine nicht unbeträchtliche Dicke auf. Beim β-Glühen eines solchen Werkstückes ist zum Erzielen der gewünschten Eigenschaften besondere Sorgfalt notwendig. Zu diesem Zweck sind Normen entwickelt worden, nach deren Vorgaben derartige Ti-Strukturbauteile βgeglüht werden müssen. Durch die Normung des β-Glühprozesses soll gewährleistet werden, dass bei einer industriellen Anwendung des β-Glühverfahrens die Werkstücke ein möglichst einheitliches Korngefüge aufweisen. Problematisch beim β-Glühen ist, dass ein zu langes Halten des Werkstückes oberhalb seiner β-Transustemperatur zu einer unerwünschten Kornvergröberung führt. Gemäß den geltenden Normen, wie AMS-H-81200B oder DIN 65084, ist gefordert, dass das Werkstück bis auf eine Temperatur erwärmt wird, die 30°C oberhalb der β-Transustemperatur der Ti-Legierung liegt. Das oberhalb der β-Transustemperatur liegende Temperaturniveau, auf das das Werkstück zu erwärmen ist, weist eine ausreichende Temperaturdifferenz zu der β-Transustemperatur auf, das auch unter Berücksichtigung der systembedingten Temperaturtoleranzen (β-Transustemperatur, Ofentemperatur) sichergestellt ist, dass das Werkstück insgesamt bei Erreichen des Temperaturniveaus oberhalb der β-Transustemperatur erwärmt ist. Hinsichtlich der eingestellten Ofentemperatur wird in aller Regel ein Toleranzbereich von ±14°C vorgegeben. Durchgeführt wird ein β-Glühen gemäß diesen Vorgaben durch Erwärmen des Werkstückes in einem Ofen. Überschreitet die Werkstücktemperatur die untere Toleranzgrenze des vordefinierten Temperaturniveaus (Tβ+30°C-14°C) bestimmt dieses den Zeitpunkt des Beginns der Haltezeit. Die Haltezeit selbst ist beispielsweise mit 30 Minuten vorgegeben. Demzufolge wird das Werkstück in dem Ofen für die Dauer der Haltezeit auf einem Temperaturniveau oberhalb von Tβ+30°-14°C belassen und anschließend einem Abkühlprozess unterworfen.Workpieces made of Ti alloys may be structural components, for example for use in aircraft construction. Such structural components typically have a not inconsiderable thickness. When β-annealing such a workpiece special care is required to achieve the desired properties. For this purpose, standards have been developed according to which specifications such Ti structural components must be annealed. By standardizing the β-annealing process, it is intended to ensure that in an industrial application of the β-annealing process, the workpieces have as uniform a grain structure as possible. The problem with β-annealing is that too long holding of the workpiece above its β-transus temperature leads to undesired grain coarsening. According to the applicable standards, such as AMS-H-81200B or DIN 65084, it is required that the workpiece is heated to a temperature which is 30 ° C above the β-transus temperature of the Ti alloy. The temperature level above the β-transus temperature, to which the workpiece is to be heated, has a sufficient temperature difference to the β-transus temperature, which is also ensured taking into account the system-related temperature tolerances (β-transus temperature, furnace temperature) that the workpiece as a whole Reaching the temperature level is heated above the β-transus temperature. With regard to the set oven temperature, a tolerance range of ± 14 ° C is usually specified. A β-anneal is performed according to these specifications by heating the workpiece in an oven. If the workpiece temperature exceeds the lower tolerance limit of the predefined temperature level (T β + 30 ° C-14 ° C), this determines the time at which the holding time begins. The holding time itself is given as 30 minutes, for example. Accordingly, the workpiece is left in the oven for the duration of the holding time at a temperature level above T β + 30 ° -14 ° C and then subjected to a cooling process.

Ein solches Verfahren ist vom Prinzip her aus GB 1,141,409 bekannt. Beschrieben ist in diesem Dokument ein Verfahren zur Kornfeinung der Mikrostruktur einer α- oder α-β-Titanlegierung. Das Werkstück wird auf eine Temperatur oberhalb der β-Transustemperatur erwärmt, um eine im Wesentlichen vollständige Umwandlung in die β-Phase zu erhalten. Auf dieser Temperatur wird das Werkstück so lange gehalten, bis hinreichend sichergestellt ist, dass eine vollständige Konversion in die β-Phase stattgefunden hat. Als Beispiel wird eine Haltezeit von einer Stunde angegeben. Anschließend wird das Werkstück abgeschreckt, und zwar auf eine Temperatur hinreichend weit unterhalb der β-Transustemperatur, um einen wesentlichen Anteil der β-Phase in eine α-Phase oder eine α-Äquivalent-Phase zu bringen. In einem nachfolgenden Schritt wird das Formstück plastisch deformiert. Die Glühung bezieht sich bei diesem Dokument auf einen Zwischenschritt in der Herstellung eines Materials im Zustand "annealed" mit einer Gefügestruktur aus globularer α-Phase, die nach dem β-Glühen und nach einer weiteren Verformung eingestellt wird. In diesem Dokument wird keine β-Glühung, die eine Endwarmbehandlung darstellt beschrieben, mit dem die Korngröße des β-Gefüges verfeinert wird, wie dieses Eingangs erwähnt ist.Such a method is in principle GB 1,141,409 known. Described in this document is a method of grain refining the microstructure of an α- or α-β-titanium alloy. The workpiece is heated to a temperature above the β-transus temperature to obtain substantially complete conversion to the β-phase. At this temperature, the workpiece is held until it is sufficiently certain that complete conversion to the β phase has occurred. As an example, a hold time of one hour is given. Subsequently, the workpiece is quenched to a temperature sufficiently low below the β-transus temperature to bring a substantial portion of the β-phase into an α-phase or an α-equivalent phase. In a subsequent step, the fitting is plastically deformed. Annealing in this document refers to an intermediate step in the preparation of an annealed material having a globular α-phase microstructure that is adjusted after β-annealing and after further deformation. This document does not describe a β-anneal, which is a final heat treatment, which refines the grain size of the β-structure, as this entry is mentioned.

Es hat sich gezeigt, dass trotz der normativen Vorgaben zum β-Glühen von Werkstücken aus einer Titanlegierung diese nicht mit der notwendigen Prozesssicherheit hergestellt werden können, diese sich mithin hinsichtlich ihres Gefüges und damit ihrer Eigenschaften trotz gleicher Verfahrensparameter voneinander unterscheiden können. Dieses ist jedoch unerwünscht.It has been shown that despite the normative specifications for the β-annealing of workpieces made of a titanium alloy, these can not be produced with the necessary process reliability, which therefore can differ from each other in terms of their microstructure and thus their properties despite the same process parameters. This is undesirable.

Ausgehend von diesem diskutierten Stand der Technik liegt der Erfindung daher die Aufgabe zugrunde, ein eingangs genanntes Verfahren dergestalt auszubilden, dass ein β-Glühen von Werkstücken aus einer Titanlegierung mit einem höheren Maß an Prozesssicherheit möglich ist.Based on this discussed prior art, the invention is therefore the object of an initially mentioned method in such a way that a β-annealing of workpieces made of a titanium alloy with a higher degree of process reliability is possible.

Diese Aufgabe wird erfindungsgemäß durch ein Verfahren gemäß Anspruch 1 gelöst.This object is achieved by a method according to claim 1.

Im Unterschied zu der herrschenden Meinung, die Ofentemperatur lediglich knapp über die β-Transustemperatur einzustellen, um eine Kornvergröberung durch eine zu hohe Temperatur zu vermeiden, wird bei dem vorgeschlagenen Verfahren der Ofen auf eine Temperatur eingestellt, die sich oberhalb desjenigen Temperaturniveaus befindet, bei dessen Überschreiten die Haltezeit zu laufen beginnt. Ausgenutzt wird bei diesem Verfahren die Eigenschaft, dass innerhalb des betrachteten Temperaturfensters oberhalb der β-Transustemperatur die Temperatur nur einen untergeordneten Einfluss auf das Kornwachstum hat. Entscheidend für das Kornwachstum und die Korngröße des β-geglühten Werkstückes ist vielmehr die Haltezeit. Durch Einstellen der Ofentemperatur auf eine Temperatur mit einer deutlichen Differenz zu derjenigen Temperatur, bei der die Zeitspanne des Haltens beginnt, wird erreicht, dass die Zeitspanne zwischen dem Zeitpunkt, in dem das Werkstück seine β-Transustemperatur überschreitet und dem Erreichen des den Beginn der Haltezeit bestimmenden Temperaturniveaus gegenüber einem herkömmlichen β-Glühen infolge des rascheren Erwärmens des Werkstückes durch die erfindungsgemäß eingestellte höhere Ofentemperatur erheblich kürzer ist. Ausgenutzt wird bei diesem Verfahren auch das Aufheizverhalten eines Ti-Werkstückes, dessen Aufheizgradient mit zunehmender Temperatur abnimmt. Der Abschnitt der Aufheizkurve des Werkstückes zwischen seiner β-Transustemperatur und dem Temperaturniveau der Haltezeit befindet-sich in einem Abschnitt der Aufheizkurve mit einem höheren Gradienten, verglichen mit dem herkömmlichen β-Glühprozess. Durch Verkürzen dieser, nicht zur Haltezeit zählenden Zeitspanne, in der eine Umwandlung in β-Phase bereits stattfindet, ist der Umfang dieser Umwandlung und das damit einhergehende Kornwachstum deutlich reduziert. Dieses macht sich gerade bei dickeren Werkstücken bemerkbar, die eine entsprechend geringe Aufheizgeschwindigkeit vor allem in dem letzten Abschnitt ihrer Aufheizkurve aufweisen und daher die Zeitspanne zwischen dem Zeitpunkt des Überschreiten der β-Transustemperatur und dem Beginn der Haltezeit entsprecht lang ist. Bei vorbekannten Verfahren hatte dies zur Folge, dass die vorgegebene Haltezeit erheblich kürzer war als diejenige Zeit, die das Werkstück erwärmt werden musste, um von seiner β-Transustemperatur auf das Temperaturniveau zum Halten erwärmt zu werden.Unlike the prevailing view that the oven temperature should be set just above the β-transus temperature to avoid grain coarsening due to too high a temperature, in the proposed method the oven is set at a temperature above that temperature level at which Exceeding the hold time begins to run. Exploited in this process the property that within the observed temperature window above the β-transus temperature, the temperature has only a minor influence on the grain growth. Decisive for the grain growth and the grain size of the β-annealed workpiece is rather the holding time. By setting the oven temperature to a temperature significantly different from the temperature at which the hold period begins, the time between when the workpiece exceeds its β-transus temperature and reaching the onset of holding time is achieved determining temperature levels compared to a conventional β-annealing as a result of the faster heating of the workpiece by the inventively set higher furnace temperature is considerably shorter. The heating behavior of a Ti workpiece, whose heating gradient decreases with increasing temperature, is also utilized in this method. The portion of the heating curve of the workpiece between its β-transus temperature and the temperature level of the holding time is in a portion of the heating curve having a higher gradient compared to the conventional β-annealing process. By shortening this non-dwell time period, in which β-phase conversion is already taking place, the amount of this conversion and concomitant grain growth is significantly reduced. This is particularly noticeable in thicker workpieces, which have a correspondingly low heating rate, especially in the last section of their heating curve and therefore the time between the time of exceeding the β-transus temperature and the beginning of the holding time is long. In prior art methods, this meant that the predetermined hold time was significantly shorter than the time that the workpiece needed to be heated to be heated from its β-transus temperature to the hold temperature level.

Die Ofeneinstelltemperatur wird man in Abhängigkeit von der Ti-Legierung und der Geometrie des Werkstückes einstellen. Es wird als ausreichend angesehen, wenn die Ofeneinstelltemperatur 50°C oberhalb der β-Transustemperatur liegt und damit deutlich oberhalb des für das Halten vorgesehenen Temperaturniveaus von Tβ+30°C-14°C. Aus ökonomischen Gründen wird man die Ofeneinstelltemperatur nicht zu hoch einstellen. Die maximale Ofeneinstelltemperatur wird man in Abhängigkeit von dem temperaturbedingten Korngrößenwachstum und der vorgesehenen Haltezeit und der erwarteten Zeitspanne wählen, die für das Erwärmen des Werkstückes von seiner β-Transustemperatur auf das Temperaturniveau der Haltezeit benötigt wird. Versuche haben gezeigt, dass selbst eine Ofeneinstelltemperatur von Tβ+100°C zu den erwarteten Ergebnissen führt, ohne, bedingt durch die zunehmende Erwärmung während der Haltezeit, ein zu großes Kornwachstum hinnehmen zu müssen. Bei einer Ofeneinstelltemperatur von Tβ+100°C ist die Zeitspanne für das Erwärmen des Werkstückes von seiner β-Transustemperatur auf das Temperaturniveau der Haltezeit entsprechend kurz. Bei einer Durchführung des Verfahrens mit einer Ofeneinstelltemperatur zum Erwärmen des Werkstückes, die, wie bei dem vorstehenden Beispiel beschrieben, erheblich oberhalb der β-Transustemperatur liegt, ist es möglich, nach Erreichen der für das Halten vorgesehenen Temperatur die Ofentemperatur eine Temperatur, die nur etwas oberhalb der β-Temperatur liegt, abzusenken. Dieses wiederum reduziert ein temperaturbedingtes Kornwachstum.The oven set temperature will be adjusted depending on the Ti alloy and the geometry of the workpiece. It is considered sufficient if the Ofeneinstelltemperatur is 50 ° C above the β transus temperature and thus well above the provided for holding temperature levels of T β + 30 ° C-14 ° C. For economic reasons, the oven setting temperature will not be set too high. The maximum oven setting temperature will depend on the temperature Select grain size growth and the intended holding time and the expected time required for heating the workpiece from its β-transus temperature to the temperature level of the holding time. Tests have shown that even a Ofeneinstelltemperatur of T β + 100 ° C leads to the expected results, without having to accept conditionally by the increasing warming during the holding time, a too large grain growth. At a furnace set temperature of T β + 100 ° C, the time for heating the workpiece from its β-transus temperature to the temperature level of the hold time is correspondingly short. In carrying out the method with a furnace setting temperature for heating the workpiece which, as described in the above example, is considerably above the β-transus temperature, it is possible, after reaching the holding temperature, the furnace temperature a temperature which is only a little above the β-temperature is lower. This in turn reduces temperature-induced grain growth.

Durch das beanspruchte Verfahren wird erstmals vorgeschlagen, die Ofentemperatur als Stellgröße einzusetzen, um dem Prozess einer β-Glühung eines aus einer Ti-Legierung hergestellten Werkstückes nicht unerheblich zu verbessern, insbesondere die mit diesem Warmbehandlungsverfahren hergestellten Werkstücke prozesssicher hinsichtlich in der gewünschten Eigenschaft herzustellen zu können. Dabei kann durchaus vorgesehen sein, die Ofentemperatur als aktive Stellgröße einzusetzen, die, nachdem das Werkstück eine vorbestimmte Temperatur erreicht hat, von einer ersten Einstelltemperatur abgesenkt wird.By the claimed method is proposed for the first time to use the furnace temperature as a manipulated variable to not insignificantly improve the process of a β-annealing of a workpiece made of a Ti alloy, in particular to be able to produce the workpieces produced by this heat treatment process with respect to in the desired property , It may well be provided to use the furnace temperature as an active manipulated variable, which, after the workpiece has reached a predetermined temperature, is lowered by a first set temperature.

Nachfolgend ist die Erfindung unter Bezugnahme auf die beigefügten Figuren nochmals eingehender beschrieben. Es zeigen:

Fig. 1
eine schematisiert dargestellte Aufheizkurve zum Darstellen eines aus einer Ti-Legierung bestehenden Werkstückes zum Durchführen einer β-Glühung nach dem erfindungsgemäßen Verfahren in einer Gegenüberstellung zu der Aufheizkurve eines aus derselben Legierung bestehenden Werkstückes gemäß dem herkömmlichen β-Glühverfahren und
Fig. 2
ein Diagramm darstellend das Kornwachstum eines Werkstückes aus einer Ti-Legierung in Abhängigkeit von der Haltezeit bei unterschiedlichen Temperaturen.
The invention will be described in more detail below with reference to the attached figures. Show it:
Fig. 1
a schematically illustrated heating curve for representing a Ti alloy existing workpiece for performing a β-annealing according to the inventive method in a comparison to the heating curve of an existing alloy of the same workpiece according to the conventional β-annealing method and
Fig. 2
a graph showing the grain growth of a workpiece made of a Ti alloy as a function of the holding time at different temperatures.

In dem Diagramm der Figur 1 ist das erfindungsgemäße β-Glühen eines Werkstückes aus einer Ti-Legierung anhand eines Temperatur/ZeitDiagramms dargestellt. Eingetragen in das Diagramm ist die Aufheizkurve A eines Ti-Werkstückes, das bei dem dargestellten Ausführungsbeispiel aus einer Ti6A14V-Legierung hergestellt ist. Der Chemismus einer Ti6A14V-Legierung ist nachfolgend wiedergegeben: Al V Fe O C N H Y Andere, einzeln Andere, Summe Ti 5,5-6,75 3,5-4,5 max. 0,30 max. 0,20 max. 0,08 max. 0,05 max. 0,0125 max. 0,005 0,10 0,40 Rest In the diagram of FIG. 1 is the inventive β-annealing of a workpiece made of a Ti alloy based on a temperature / time diagram shown. Entered in the diagram is the heating curve A of a Ti workpiece, which is made in the illustrated embodiment of a Ti6A14V alloy. The chemistry of a Ti6A14V alloy is shown below: al V Fe O C N H Y Others, individually Others, sum Ti 5.5 to 6.75 3.5-4.5 Max. 0.30 Max. 0.20 Max. 0.08 Max. 0.05 Max. 0.0125 Max. 0.005 0.10 0.40 rest

Das Ti-Werkstück, dessen Aufheizkurve A in Figur 1 für den Prozess des β-Glühens schematisiert wiedergegeben ist, weist konkret folgende Zusammensetzung auf: Al V Fe O C N H Y Andere, einzeln Andere, Summe Ti 5,98 3,86 0,18 0,11 0,006 0,005 0,0017 < 0,005 < 0,10 < 0,30 Rest The Ti workpiece whose heating curve A in FIG. 1 is schematically shown for the process of β-annealing, concretely has the following composition: al V Fe O C N H Y Others, individually Others, sum Ti 5.98 3.86 0.18 0.11 0,006 0.005 0.0017 <0.005 <0.10 <0.30 rest

Die β-Transustemperatur Tβ der für dieses Werkstück eingesetzten Ti-Legierung liegt bei etwa 970°C. Der Ofen, in dem das Werkstück dem β-Glühverfahren unterworfen werden soll, ist bei dem dargestellten Ausführungsbeispiel auf eine Temperatur von Tβ+50°C eingestellt. Damit beträgt die Ofeneinstelltemperatur TF 1.020°C. Eingetragen sind in das Diagramm die β-Transustemperatur Tβ sowie die eingestellten Ofentemperatur TF als durchgehende Linie, wobei der Toleranzbereich der beiden Temperaturen Tβ sowie TF gerastert oberhalb und unterhalb der jeweiligen Temperatur Tβ bzw. TF eingetragen ist. Eingetragen ist ferner die Untergrenze des für das Halten des Werkstückes für den β-Glühprozess bestimmten Temperaturniveaus TH. Der Zeitpunkt des Erreichens des Werkstückes der Temperatur TH bestimmt sodann den Beginn der Haltezeit - derjenigen Zeitspanne, die das Werkstück zum bestimmungsgemäßen Ausführen des β-Glühens auf oder oberhalb der Temperatur TH zu belassen ist. Bei dem dargestellten Ausführungsbeispiel ist die Untergrenze des Temperaturniveaus für die Haltezeit diejenige Temperatur, die auch bei herkömmlichen Verfahren den Beginn der Haltezeit definiert, namentlich Tβ+30°C-14°C für die in Rede stehende Ti6A14V-Legierung.The β-transus temperature T β of the Ti alloy used for this workpiece is about 970 ° C. The furnace in which the workpiece is to be subjected to the β-annealing process is set in the illustrated embodiment to a temperature of T β + 50 ° C. Thus, the furnace setting temperature T F is 1,020 ° C. Entered into the diagram, the β-transus temperature T β and the set furnace temperature T F as a solid line, the tolerance range of the two temperatures T β and T F rasterized above and below the respective temperature T β and T F is entered. Also entered is the lower limit of the temperature level T H determined for holding the workpiece for the β-annealing process. The time of reaching the workpiece of the temperature T H then determines the beginning of the holding time - the time that the workpiece for normal execution of the β-annealing on or above the temperature T H is to be left. In the illustrated Embodiment, the lower limit of the temperature level for the holding time is the temperature that defines the start of the holding time also in conventional methods, namely T β + 30 ° C-14 ° C for the Ti6A14V alloy in question.

Die Erwärmung des Ti-Werkstückes kann ausgehend von einem kalten Ofen oder auch in einem bereits vorgewärmten Ofen erfolgen. Die Aufheizkurve A ist bestimmt durch einen sich ab einer bestimmten Temperatur zunehmend abnehmenden Erwärmungsgradienten. Je geringer die Temperaturdifferenz zwischen der aktuellen Temperatur des Werkstückes und der Ofeneinstelltemperatur TF ist, je geringer ist der Erwärmungsgradient. Im Zuge der fortschreitenden Erwärmung überschreitet die Temperatur des Werkstückes im Zeitpunkt t1 die Obergrenze der Toleranz der β-Transustemperatur Tβ. Um sicherzustellen, dass das Werkstück insgesamt auf eine Temperatur oberhalb der Obergrenze des Toleranzbereiches der β-Transustemperatur Tβ erwärmt worden ist, liegt die Untergrenze des Temperaturniveaus TH oberhalb der Obergrenze des Toleranzbereiches der β-Transustemperatur Tβ. Wenn das Werkstück im Zeitpunkt t2 die für das Halten vorgesehene Temperatur TH erreicht hat, beginnt die bezüglich ihrer Dauer vordefinierte Haltezeit, die im vorliegenden Ausführungsbeispiel mit 30 Minuten gewählt ist. Nach Ablauf der Haltezeit, die in dem Diagramm der Figur 1 im Zeitpunkt t3 eingetragen ist, wird das Werkstück aus dem Ofen entnommen und einem definierten Abkühlprozess unterworfen. Bei dem dargestellten Ausführungsbeispiel der Aufheizkurve A beträgt das Zeitintervall zwischen den Zeitpunkten t1, t2 etwa 15 - 20 Minuten.The heating of the Ti workpiece can be done from a cold oven or in an already preheated oven. The heating curve A is determined by a starting from a certain temperature increasingly decreasing heating gradient. The smaller the temperature difference between the current temperature of the workpiece and the furnace setting temperature T F , the lower the heating gradient. In the course of the progressive warming, the temperature of the workpiece at the time t 1 exceeds the upper limit of the tolerance of the β-transus temperature T β . To ensure that the workpiece as a whole has been heated to a temperature above the upper limit of the tolerance range of the β-transus temperature T β , the lower limit of the temperature level T H is above the upper limit of the tolerance range of the β-transus temperature T β . When the workpiece has reached the temperature T H intended for holding at the time t 2, the holding time, which is predefined with regard to its duration, which is selected as 30 minutes in the present exemplary embodiment, begins. After expiration of the holding time in the diagram of the FIG. 1 is entered at time t 3 , the workpiece is removed from the oven and subjected to a defined cooling process. In the illustrated embodiment, the heating curve A, the time interval between the times t 1 , t 2 is about 15 - 20 minutes.

Ist das Werkstück auf seine Haltetemperatur erwärmt worden, kann der Ofen auf ein niedrigeres Temperaturniveau abgesenkt werden. Dieses reduziert den Energieverbrauch und den, wenn auch geringen Einfluss der Temperatur auf das Kornwachstum oberhalb der β-Transustemperatur. Dieses geschieht im Zeitpunkt t2 oder kurz danach. Abgesenkt werden kann die Ofentemperatur auf die zum Halten vorgesehene Temperatur, die bei dem dargestellten Ausführungsbeispiel Tβ+30°C-14°C beträgt.If the workpiece has been heated to its holding temperature, the furnace can be lowered to a lower temperature level. This reduces the energy consumption and, albeit slight influence of the temperature on the grain growth above the β-transus temperature. This happens at time t 2 or shortly thereafter. The furnace temperature can be lowered to the temperature intended for holding, which in the exemplary embodiment illustrated is T β + 30 ° C.-14 ° C.

Dem vorstehend beschriebenen β-Glühen ist in Figur 1 das herkömmliche β-Glühen eines Ti-Werkstückes gegenübergestellt. Dieses Ti-Werkstück weist dieselbe Legierungszusammensetzung auf, wie dasjenige, welches mit dem erfindungsgemäßen β-Glühen warmbehandelt worden ist. Bei dem vorbekannten β-Glühen beträgt die Ofeneinstelltemperatur TF'=Tβ+30° (1.000°C). Auch zu dieser Temperatur TF' ist der Toleranzbereich oberhalb und unterhalb durch eine Rasterung kenntlich gemacht. Aufgrund der geringeren Ofeneinstelltemperatur TF', verglichen mit dem Ausführungsbeispiel gemäß der Erfindung, verläuft der Erwärmungsprozess des Werkstückes, in Figur 1 anhand seiner Aufwärmkurve A' strichpunktiert gezeigt, insgesamt langsamer. Im Zeitpunkt t1' wird die Obergrenze des Toleranzbereiches der β-Transustemperatur überschritten und im Zeitpunkt t2' die Untergrenze des Temperaturniveaus TH der Haltezeit. Wird im Zeitpunkt t2' das Temperaturniveau TH überschritten, beginnt die 30-minütige Haltezeit.The β-anneal described above is in FIG. 1 contrasting the conventional β-annealing of a Ti workpiece. This Ti workpiece has the same alloy composition as that which has been heat-treated with the β-annealing of the present invention. In the prior art β-annealing, the furnace setting temperature is T F '= T β + 30 ° (1,000 ° C). Also at this temperature T F ', the tolerance range above and below is indicated by a screening. Due to the lower Ofeneinstelltemperatur T F ', compared with the embodiment according to the invention, the heating process of the workpiece, in FIG. 1 shown dash-dotted on the basis of its warm-up curve A ', overall slower. At time t 1 ', the upper limit of the tolerance range of the β-transus temperature is exceeded and at time t 2 ' the lower limit of the temperature level T H of the holding time. If the temperature level T H is exceeded at time t 2 ', the 30-minute hold time begins.

Die Gegenüberstellung der beiden Aufheizkurven A, A' macht zum einen deutlich, dass der Beginn der Haltezeit bezogen auf den Gesamtprozess bei dem herkömmlichen β-Glühen (Aufheizkurve A') später einsetzt und daher die Prozessdauer länger ist als bei dem zur Aufheizkurve A beschriebenen erfindungsgemäßen Verfahren. Bei dem herkömmlichen Verfahren beträgt das Zeitintervall zwischen den Zeitpunkten t1' und t2' etwa 40 Minuten und ist daher etwa doppelt so lange wie bei dem zu der beanspruchten Erfindung im Wege des vorstehenden Ausführungsbeispiels beschriebenen Verfahren. Die bei dem erfindungsgemäßen Verfahren kürzere Zeitspanne zwischen dem Zeitpunkt des Erreichens der β-Transustemperatur bzw. der Untergrenze des Toleranzbereiches derselben und dem Erreichen der Temperatur TH erklärt nicht nur die höhere Prozesssicherheit dieses Verfahrens sondern auch, dass das mit diesem Verfahren β-geglühte Werkstück insgesamt feinkörniger ist und eine homogenere Korngrößenverteilung aufweist.The comparison of the two Aufheizkurven A, A 'makes it clear that the beginning of the holding time based on the overall process in the conventional β-annealing (heating curve A') later begins and therefore the process duration is longer than in the inventive heating curve A described Method. In the conventional method, the time interval between the times t 1 'and t 2 ' is about 40 minutes and is therefore about twice as long as in the method described in the above embodiment for the claimed invention. The shorter time interval in the inventive method between the time of reaching the β-transus temperature or the lower limit of the tolerance range thereof and the achievement of the temperature T H not only explains the higher process reliability of this method but also that the β-annealed workpiece with this method overall fine-grained and has a more homogeneous particle size distribution.

Bei den vorbeschriebenen Ti-Werkstücken, deren Aufheizkurven A, A' in Figur gegenüber gestellt sind, handelte es sich um zylindrische Probenkörper mit einem Durchmesser von 200 mm und einer Höhe von 125 mm. Im Anschluss an die jeweilige β-Glühung wurde eine Korngrößenuntersuchung an den beiden Werkstücken durchgeführt. Als Ergebnis zeigte sich, dass bei gemäß dem Stand der Technik durchgeführtem β-Glühen eine durchschnittliche Korngröße von 0,74 mm erzielt worden ist. Die gemäß dem erfindungsgemäßen Verfahren β-geglühte Probe wies dagegen eine durchschnittliche Korngröße von nur 0,58 mm auf. Zudem war festzustellen, dass die Abweichung der Korngrößen von dem vorgenannten Mittelwert bei der erfindungsgemäß β-geglühten Probe kleiner ist als bei derjenigen, die einem herkömmlichen β-Glühen unterworfen worden ist.In the above-described Ti workpieces, the heating curves A, A 'are set in Figure opposite, it was cylindrical specimen with a diameter of 200 mm and a height of 125 mm. Following the respective β-annealing, a particle size analysis was carried out on the two workpieces. As a result, it has been found that in the β-annealing performed according to the prior art, an average grain size of 0.74 mm has been achieved. The according to In contrast, the β-annealed sample according to the invention had an average grain size of only 0.58 mm. In addition, it was found that the deviation of the grain sizes from the aforementioned mean value is smaller in the case of the β-annealed sample according to the invention than in the case of that which has been subjected to conventional β-annealing.

Figur 2 zeigt ein Korngrößenvergleichsdiagramm, in dem in Abhängigkeit von der Haltezeit der auch für die Glühversuche verwendeten Legierung Ti6Al4V die Korngröße aufgetragen ist. Eingetragen sind in dem Diagramm vier, sich hinsichtlich der Temperatur ihrer Haltezeit unterscheidende Kurven. Die vier Proben wiesen folgende Legierungszusammensetzung auf: Al V Fe O C N H Y Andere, einzeln Andere, Summe Ti 5,92 3,82 0,18 0,11 0,006 0,005 0,0035 < 0,005 < 0,10 < 0,30 Rest FIG. 2 shows a grain size comparison diagram in which, depending on the holding time of the Ti6Al4V alloy used for the annealing experiments, the grain size is plotted. Registered in the diagram are four curves differing in the temperature of their holding time. The four samples had the following alloy composition: al V Fe O C N H Y Others, individually Others, sum Ti 5.92 3.82 0.18 0.11 0,006 0.005 0.0035 <0.005 <0.10 <0.30 rest

Die in Figur 2 aufgetragenen Kurven machen deutlich, dass in dem betrachteten Temperaturfenster (Tβ+30C° bis Tβ+100C°) die Korngröße maßgeblich von der Haltezeit und nur untergeordnet von dem Temperaturniveau der Haltezeit abhängig ist. Die Kurven weichen nicht signifikant voneinander ab und befinden sich innerhalb der Messgenauigkeit. Dieses festzustellen war unerwartet und entsprach nicht der herrschenden Meinung.In the FIG. 2 Plotted curves make it clear that in the considered temperature window (T β + 30C ° to T β + 100C °), the grain size is significantly dependent on the holding time and only subordinate to the temperature level of the holding time. The curves do not differ significantly and are within the measurement accuracy. Determining this was unexpected and did not meet the prevailing opinion.

Aus der Beschreibung des erfindungsgemäßen Verfahrens wird deutlich, dass, je höher die Ofeneinstelltemperatur ist und damit je größer die Temperaturdifferenz zwischen der Ofeneinstelltemperatur und der Temperatur TH, die den Beginn des Haltens definiert, ist, je kürzer ist die Zeitspanne zwischen dem Zeitpunkt des Erreichens der β-Transustemperatur und der Temperatur TH. Mithin befindet sich dieser Zeitabschnitt in einem Bereich der Aufheizkurve mit einem größeren Erwärmungsgradienten. Da in dem Temperaturintervall zwischen Tβ und TH bereits Phasenänderungen eintreten können, diese Zeitspanne jedoch nicht zur Haltezeit zählt, wird deutlich, dass diese in Bezug auf die normierten Verfahren nicht definierte Zeitspanne bei dem erfindungsgemäßen Verfahren erheblich minimiert worden ist. Folglich ist die Prozesssicherheit der mit diesem Verfahren warmbehandelten Ti-Werkstücke entsprechend größer.From the description of the method according to the invention, it is clear that the higher the furnace setting temperature, and hence the greater the temperature difference between the furnace setting temperature and the temperature T H defining the start of holding, the shorter the time between the time of reaching the β-transus temperature and the temperature T H. Consequently, this period is located in a region of the heating curve with a larger heating gradient. Since phase changes can already occur in the temperature interval between T β and T H , but this period of time does not count as holding time, it becomes clear that this time span, which has not been defined in relation to the normalized methods, has been considerably minimized in the method according to the invention. Consequently, the process reliability is with this method heat treated Ti workpieces correspondingly larger.

Die Erfindung ist anhand von Ausführungsbeispielen beschrieben worden. Versuche haben gezeigt, dass sich ebenfalls andere Ti-Legierungen zum Durchführen dieses β-Glühens eignen, wie beispielsweise eine Ti6Al4V ELI oder eine Ti 6-22-22-Legierung. Darüber hinaus eignet sich dieses β-Glühverfahren auch für andere α-β-Ti-Legierungen.The invention has been described with reference to embodiments. Experiments have shown that other Ti alloys are also suitable for performing this β-annealing, such as a Ti6Al4V ELI or a Ti 6-22-22 alloy. In addition, this β-annealing method is also suitable for other α-β-Ti alloys.

Claims (5)

  1. Method for the heat treatment of a workpiece produced from a titanium alloy for obtaining a fine-grained microstructure by annealing the workpiece above its ß-transus temperature (Tß) (ß-annealing), wherein the workpiece is heated in a furnace to a temperature level (TH) above it ß-transus temperature (Tß), and the temperature level (TH) has its lower limit at the temperature determined for the subsequent holding of the workpiece for the ß-annealing process, and the reaching of the temperature level (TH) determines the beginning of a predefined holding time, and the workpiece is left at the temperature (TH) for the duration of the holding time before being subjected to a cooling process, characterised in that the heat treatment is carried out in a furnace of which the furnace temperature (TF) set for the heating of the workpiece to the temperature level intended for carrying out the holding procedure is above the temperature level (TH) which determines the beginning of the holding time, wherein the furnace temperature set for the heating of the workpiece to its holding temperature (TH) is at least 20°C above the temperature level (TH) intended for the holding process.
  2. Method according to claim 1, characterised in that, after the heating of the workpiece to the temperature level (TH), the furnace temperature is reduced to a lower furnace temperature.
  3. Method according to claim 2, characterised in that the furnace is reduced to the temperature level (TH) which determines the beginning of the holding period.
  4. Method according to one of claims 1 to 3, characterised in that the furnace temperature which is set is 50°C above the ß-transus temperature (Tß).
  5. Method according to one of claims 1 to 4, characterised in that the furnace temperature which is set for heating the workpiece to its holding temperature (TH) is not more than 100°C above the temperature level (TH) intended for the holding process.
EP10702655.1A 2009-02-05 2010-01-29 Method for the beta annealing of a workpiece produced from a ti alloy Active EP2393952B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102009003430A DE102009003430A1 (en) 2009-02-05 2009-02-05 A method of heat treating a Ti alloy workpiece
PCT/EP2010/051078 WO2010089256A1 (en) 2009-02-05 2010-01-29 Method for the beta annealing of a workpiece produced from a ti alloy

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Publication Number Publication Date
EP2393952A1 EP2393952A1 (en) 2011-12-14
EP2393952B1 true EP2393952B1 (en) 2014-10-29

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EP10702655.1A Active EP2393952B1 (en) 2009-02-05 2010-01-29 Method for the beta annealing of a workpiece produced from a ti alloy

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US (1) US8388776B2 (en)
EP (1) EP2393952B1 (en)
DE (1) DE102009003430A1 (en)
ES (1) ES2528941T3 (en)
WO (1) WO2010089256A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106826118A (en) * 2017-02-08 2017-06-13 大连盛辉钛业有限公司 A kind of preparation method for manufacturing the medical titanium alloy bar of pedicle screw

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2927335B1 (en) 2014-04-03 2016-07-13 Otto Fuchs KG Aluminium bronze alloy, method for manufacturing the same and product made of aluminium bronze
DE102014106933A1 (en) 2014-05-16 2015-11-19 Otto Fuchs Kg Special brass alloy and alloy product

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SE342850B (en) * 1966-01-24 1972-02-21 Continental Titanum Metals Cor
JP2841766B2 (en) * 1990-07-13 1998-12-24 住友金属工業株式会社 Manufacturing method of corrosion resistant titanium alloy welded pipe
US5705794A (en) 1991-10-15 1998-01-06 The Boeing Company Combined heating cycles to improve efficiency in inductive heating operations
US5277718A (en) * 1992-06-18 1994-01-11 General Electric Company Titanium article having improved response to ultrasonic inspection, and method therefor
US5861070A (en) * 1996-02-27 1999-01-19 Oregon Metallurgical Corporation Titanium-aluminum-vanadium alloys and products made using such alloys
US20010041148A1 (en) * 1998-05-26 2001-11-15 Kabushiki Kaisha Kobe Seiko Sho Alpha + beta type titanium alloy, process for producing titanium alloy, process for coil rolling, and process for producing cold-rolled coil of titanium alloy

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106826118A (en) * 2017-02-08 2017-06-13 大连盛辉钛业有限公司 A kind of preparation method for manufacturing the medical titanium alloy bar of pedicle screw

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ES2528941T3 (en) 2015-02-13
WO2010089256A1 (en) 2010-08-12
DE102009003430A1 (en) 2010-09-23
US20120000581A1 (en) 2012-01-05
US8388776B2 (en) 2013-03-05
EP2393952A1 (en) 2011-12-14

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