EP0845542B1 - Process of manufacturing semi-finished products in aluminium - Google Patents
Process of manufacturing semi-finished products in aluminium Download PDFInfo
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- EP0845542B1 EP0845542B1 EP97110712A EP97110712A EP0845542B1 EP 0845542 B1 EP0845542 B1 EP 0845542B1 EP 97110712 A EP97110712 A EP 97110712A EP 97110712 A EP97110712 A EP 97110712A EP 0845542 B1 EP0845542 B1 EP 0845542B1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
- B22D21/002—Castings of light metals
- B22D21/007—Castings of light metals with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C
Definitions
- the present invention relates to a method for Manufacture of workpieces or semi-finished products from one low wear aluminum alloy with intermetallic Phase forming additives.
- a powder with non-aluminum components a dimension of ⁇ 10 ⁇ m is obtained, and this becomes a Body formed at temperatures between 330 ° and 520 ° C is sintered.
- the aluminum alloy can be additives contain titanium and zirconium; there is also talk of an extrusion of the sintered body. It also becomes a Surface area of the body using laser beams or Plasma welding melted extremely briefly and again solidifies to achieve surface hardening.
- JP-A-5 148 563 is concerned with the production of Electrode material for electrolytic capacitors, where as Starting material an aluminum foil material by means of a Cooling roller was manufactured while doing fine dentritic intermetallic precipitates were formed. To glassy Phases, i.e. amorphous solidified phases of the aluminum matrix in These foils are used to convert a crystalline form melted for further processing, the intermetallic phases are not yet fluid. The Material then slows down on a single roller solidifies to a crystalline solidification of the Aluminum matrix to maintain the thin films. Electrolytic capacitors are then produced from this.
- the present invention is based on the object To create methods of the type described above with which also includes thick-walled, voluminous workpieces or semi-finished products made of a low-wear aluminum alloy in the Casting processes can be made that are qualitative are high.
- the process is also intended to manufacture of semi-finished products, which can be found in a subsequent Have the forming process formed into workpieces without doing so due to inhomogeneities the positive properties of the Casting material get lost.
- This task is carried out in a method of the type mentioned solved according to the invention in that in a first Step a melt the alloy in such a low amount Dimension is shed that high Cooling rate is reached that the forming precipitation crystals of the intermetallic Phases distributed homogeneously and with a defined grain size the melt are excreted; that in the first Step material obtained at temperatures in the range of the heterogeneous area between aluminum melt and intermetallic phase and the aluminum so far that the alloy is melted under Gravity is fluid and then that one Workpiece or a semi-finished product with compared to the dimension of the Primary material of larger dimensions is created.
- the melt is according to the invention cooled very quickly, so that a homogeneous distribution of the precipitating intermetallic phases or Precipitation crystals is reached. While due to Diffusion processes at very slow Solidification processes inside a thick-walled Cast the precipitation crystals a dimension of 80 ⁇ m and above can be according to the invention by rapid cooling, a fine-grained, homogeneous distribution the precipitation crystals "frozen". This is according to of the invention achieved in that the melt in the first step is cast with a small dimension, which depending on the available Cooling capacity less than 50 mm, preferably less than Is 20 mm.
- the melt can be used for technical implementation in continuous casting "finger thick" or in ingots or tapes, in particular also be cast on a casting wheel.
- the intermetallic phases succeed in train defined grain size.
- the grain size should be in in any case less than 80 ⁇ m, preferably less than 40 ⁇ m and particularly preferably less than 20 ⁇ m be. The best results are achieved when the Dimension or the cooling rate so high is that grain sizes of less than 5 ⁇ m result.
- intermetallic phases are preferably aluminides, but in principle it could also be compounds of the alloying elements.
- the alloying elements for forming aluminides as intermetallic phases are preferably titanium and zircon which crystallize out to form Al 3 Ti and Al 3 Zr. If titanium is added, the remelting temperature in the second step of the method according to the invention is about 800 ° Celsius.
- the aluminum matrix is already liquid again at this temperature, but the titanium aluminide formed, Al 3 Ti, with a melting point of 1460 ° Celsius is still solid. Due to the low solubility of the Al 3 Ti in the aluminum melt of about 0.4%, the precipitation crystals are largely preserved and are not dissolved.
- the temperature to which the starting material is reheated in the second step of the process according to the invention must be kept well below the melting temperature of the intermetallic phase in question, but on the other hand it must be so high that a sufficient proportion of melt for the subsequent shaping into the desired dimensions is available.
- the subsequent shaping or reshaping can be done by simple gravity casting but also in pressure or centrifugal casting.
- the semi-finished products with larger dimensions that are produced in this way are particularly suitable for forming, for example, in the extrusion process, forging, rolling or tixocasting, since the fine-grained hard precipitation crystals are not destroyed during the forming processes and the wear-reducing phases are evenly distributed.
- additives such as copper, Magnesium, manganese are used, which is the matrix hardness increase the alloy. It can also prove to be turn out to be advantageous if other hard crystals, such as e.g. Silicon to be embedded in the aluminum matrix.
- the micrograph according to FIG. 1 shows a fine-grained, homogeneous structure of a low-wear aluminum alloy, titanium and other additives which increase the matrix hardness being added.
- the dark phases represent precipitation crystals.
- a strand in the order of magnitude of approx. 20 mm in diameter was cast and thereby solidified so quickly that precipitation crystals in the form of titanium aluminide, Al 3 Ti, homogeneously distributed with a dimension of less than 80 microns.
- the desired grain size is set via the strand dimensions and the heat dissipation conditions.
- the approximately "finger-thick" continuous casting is then brought back to a temperature of approximately 800 ° Celsius in a second process step, at which the aluminum matrix of the primary material is at least partially melted, so that a sufficient amount of melt for molding or casting a workpiece is compared the dimension of the finger-thick strand of the primary material of larger dimension or for the casting of a semi-finished product, such as a thick rug, for a subsequent extrusion process.
- the remelting temperature in the second step of the process is significantly below the melting temperature of the titanium aluminide and furthermore the solubility of the titanium aluminide in the aluminum melt at the remelting temperature is only 0.4%, the fine-grained precipitates of the titanium aluminide are largely retained and also characterize the structure of the final workpiece or semi-finished product.
Description
Die vorliegende Erfindung betrifft ein Verfahren zum Herstellen von Werkstücken oder Halbzeugen aus einer verschleißarmen Aluminium-Legierung mit intermetallische Phasen bildenden Zusätzen.The present invention relates to a method for Manufacture of workpieces or semi-finished products from one low wear aluminum alloy with intermetallic Phase forming additives.
Die Herstellung von Werkstücken oder Halbzeugen aus einer verschleißarmen Aluminium-Legierung im Gießverfahren war seither qualitativ hochstehend nur bei dünnwandigen Werkstücken oder Halbzeugen möglich. Bei dickwandigen Werkstücken oder Halbzeugen mit größeren Abmessungen ergibt sich zwangsläufig eine sehr langsame Erstarrungsgeschwindigkeit mit der Folge, dass sich im inneren eines voluminösen Gußstücks sehr große Ausscheidungskristalle der intermetallischen Phasen ausbilden. Dies beeinträchtigt die Qualität des Gußstücks durch die homogene Gefügeausbildung. Handelt es sich bei dem Gußstück um ein Halbzeugprodukt, so werden diese großen Ausscheidungskristalle bei der nachfolgenden Umformung, etwa im Strangpress oder Walzprozess, gebrochen bzw. zerstört, was zu einer erheblichen Verringerung der Festigkeit des Werkstoffs führt.The production of workpieces or semi-finished products from one low-wear aluminum alloy in the casting process since then high quality only for thin-walled Workpieces or semi-finished products possible. With thick-walled Workpieces or semi-finished products with larger dimensions inevitably a very slow one Solidification speed with the consequence that in the very large inside of a voluminous casting Precipitation crystals of the intermetallic phases form. This affects the quality of the casting due to the homogeneous structure. It is the casting around a semi-finished product, these become large Precipitation crystals in the subsequent forming, for example in the extrusion or rolling process, broken or destroyed, resulting in a significant reduction in the Strength of the material leads.
Es war also bislang nicht möglich, bei der Herstellung dickwandiger Werkstücke oder Halbzeuge eine gleichmäßige sehr feinkörnige Ausscheidung von intermetallischen Hartphasen zu erreichen, wobei unter einer feinkörnigen Verteilung eine solche verstanden werden soll, bei der die Ausscheidungskristalle eine Korngröße von deutlich weniger als 80 µm, im bevorzugten Fall weniger als 20 µm aufweisen.So far it has not been possible to manufacture thick-walled workpieces or semi-finished products very fine-grained excretion of intermetallic To achieve hard phases, taking a fine-grained Distribution should be understood as one in which the Precipitation crystals have a grain size of significantly less have than 80 microns, in the preferred case less than 20 microns.
Es ist zwar bekannt, verhältnismäßig dickwandige Werkstücke durch eine sogenannte Sprühkompaktierung mit möglichst feinkörnigen Ausscheidungskristallen herzustellen. Dabei wird unter Verwendung einer aufwendigen unter Schutzgasatmosphäre arbeitenden Apparatur ein Strahl aus flüssiger Aluminium-Schmelze zerstäubt und auf einen entsprechenden Zielkörper aufgesprüht, bis das gewünschte Werkstück quasi Schicht für Schicht aufgebaut wurde. Die Durchführung des Verfahrens ist kompliziert, sehr teuer und mit einem hohem Gefahrenpotential verbunden. Although it is known, relatively thick-walled workpieces by means of a so-called spray compaction, if possible to produce fine-grained precipitation crystals. there is made using an elaborate In a protective gas atmosphere working equipment a jet liquid aluminum melt atomized and on one sprayed corresponding target body until the desired Workpiece was built up layer by layer. The Implementation of the procedure is complicated, very expensive and associated with a high risk potential.
Gemäß US-A-4,711,823 wird durch Zerstäuben einer Aluminiumlegierung ein Pulver mit Nichtaluminiumkomponenten einer Abmessung < 10 µm erhalten, und daraus wird ein Körper gebildet, der bei Temperaturen zwischen 330° und 520°C gesintert wird. Die Aluminiumlegierung kann Zusätze von Titan und Zirkonium enthalten; auch ist die Rede von einer Extrusion des Sinterkörpers. Es wird ferner ein Oberflächenbereich des Körpers mittels Laserstrahlen oder Plasmaschweißen extrem kurzzeitig aufgeschmolzen und wieder erstarrt, um eine Oberflächenhärtung zu erreichen.According to US-A-4,711,823 by atomizing one Aluminum alloy a powder with non-aluminum components a dimension of <10 µm is obtained, and this becomes a Body formed at temperatures between 330 ° and 520 ° C is sintered. The aluminum alloy can be additives contain titanium and zirconium; there is also talk of an extrusion of the sintered body. It also becomes a Surface area of the body using laser beams or Plasma welding melted extremely briefly and again solidifies to achieve surface hardening.
JP-A-5 148 563 befasst sich mit der Herstellung von Elektrodenmaterial für Elektrolytkondensatoren, wobei als Ausgangsmaterial ein Aluminiumfolienmaterial mittels einer Kühlwalze hergestellt wurde und dabei feine dentritische intermetallische Ausscheidungen gebildet wurden. Um glasige Phasen, d.h. amorph erstarrte Phasen der Aluminiummatrix in eine kristalline Form zu überführen, werden diese Folien zur weiteren Verarbeitung erschmolzen, wobei die intermetallischen Phasen noch nicht flüssig werden. Der Werkstoff wird dann auf einer Einzelwalze langsamer erstarrt, um eine kristalline Erstarrung der Aluminiummatrix der nach wie vor dünnen Folien zu erhalten. Hieraus werden dann Elektrolytkondensatoren hergestellt.JP-A-5 148 563 is concerned with the production of Electrode material for electrolytic capacitors, where as Starting material an aluminum foil material by means of a Cooling roller was manufactured while doing fine dentritic intermetallic precipitates were formed. To glassy Phases, i.e. amorphous solidified phases of the aluminum matrix in These foils are used to convert a crystalline form melted for further processing, the intermetallic phases are not yet fluid. The Material then slows down on a single roller solidifies to a crystalline solidification of the Aluminum matrix to maintain the thin films. Electrolytic capacitors are then produced from this.
Der vorliegenden Erfindung liegt die Aufgabe zugrunde ein Verfahren der eingangs beschriebenen Art zu schaffen, mit dem auch dickwandige, voluminöse Werkstücke oder Halbzeuge aus einer verschleißarmen Aluminium-Legierung im Gießverfahren hergestellt werden können, die qualitativ hochstehend sind. Das Verfahren soll ferner die Herstellung von Halbzeugen ermöglichen, die sich in einem nachfolgenden Umformprozess zu Werkstücken formen lassen, ohne dass dabei durch Inhomogenitäten die positiven Eigenschaften des Gußwerkstoffs verloren gehen.The present invention is based on the object To create methods of the type described above with which also includes thick-walled, voluminous workpieces or semi-finished products made of a low-wear aluminum alloy in the Casting processes can be made that are qualitative are high. The process is also intended to manufacture of semi-finished products, which can be found in a subsequent Have the forming process formed into workpieces without doing so due to inhomogeneities the positive properties of the Casting material get lost.
Diese Aufgabe wird bei einem Verfahren der genannten Art erfindungsgemäß dadurch gelöst, dass in einem ersten Schritt eine Schmelze der Legierung in derart geringer Abmessung vergossen wird, dass eine so hohe Abkühlungsgeschwindigkeit erreicht wird, dass die sich bildenden Ausscheidungskristalle der intermetallischen Phasen homogen verteilt und mit definierter Korngröße aus der Schmelze ausgeschieden werden; dass das im ersten Schritt erhaltene Vormaterial auf Temperaturen im Bereich des heterogenen Gebietes zwischen Aluminium-Schmelze und intermetallischer Phase erhitzt und das Aluminium soweit aufgeschmolzen wird, dass die Legierung unter Schwerkraftbedingungen fließfähig ist und dass dann ein Werkstück oder ein Halbzeug mit gegenüber der Abmessung des Vormaterials größerer Abmessung erstellt wird. This task is carried out in a method of the type mentioned solved according to the invention in that in a first Step a melt the alloy in such a low amount Dimension is shed that high Cooling rate is reached that the forming precipitation crystals of the intermetallic Phases distributed homogeneously and with a defined grain size the melt are excreted; that in the first Step material obtained at temperatures in the range of the heterogeneous area between aluminum melt and intermetallic phase and the aluminum so far that the alloy is melted under Gravity is fluid and then that one Workpiece or a semi-finished product with compared to the dimension of the Primary material of larger dimensions is created.
In dem ersten Schritt wird die Schmelze erfindungsgemäß sehr rasch abgekühlt, damit eine homogene Verteilung der sich ausscheidenden intermetallischen Phasen bzw. Ausscheidungskristalle erreicht wird. Während aufgrund von Diffussionsprozessen bei sehr langsamen Erstarrungsprozessen im inneren eines dickwandigen Gußstücks die Ausscheidungskristalle eine Abmessung von 80 µm und darüber aufweisen können, wird gemäß der Erfindung durch rasches Abkühlen eine feinkörnige homogene Verteilung der Ausscheidungskristalle "eingefroren". Dies wird gemäß der Erfindung dadurch erreicht, dass die Schmelze in dem ersten Schritt mit einer geringen Abmessung vergossen wird, die in Abhängigkeit von der zur Verfügung stehenden Kühlkapazität geringer als 50 mm, vorzugsweise geringer als 20 mm ist. Zur technischen Verwirklichung kann die Schmelze im Strangguß "fingerdick" oder in Masseln oder Bändern, insbesondere auch über ein Gießrad vergossen werden. Auf diese Weise gelingt es, die intermetallischen Phasen in definierter Korngröße auszubilden. Die Korngröße soll in jedem Fall weniger als 80 µm, bevorzugtermaßen weniger als 40 µm und besonders bevorzugtermaßen weniger als 20 µm betragen. Die besten Ergebnisse werden erzielt, wenn die Abmessung bzw. die Abkühlungsgeschwindigkeit derart hoch ist, dass Korngrößen von weniger als 5 µm resultieren.In the first step, the melt is according to the invention cooled very quickly, so that a homogeneous distribution of the precipitating intermetallic phases or Precipitation crystals is reached. While due to Diffusion processes at very slow Solidification processes inside a thick-walled Cast the precipitation crystals a dimension of 80 µm and above can be according to the invention by rapid cooling, a fine-grained, homogeneous distribution the precipitation crystals "frozen". This is according to of the invention achieved in that the melt in the first step is cast with a small dimension, which depending on the available Cooling capacity less than 50 mm, preferably less than Is 20 mm. The melt can be used for technical implementation in continuous casting "finger thick" or in ingots or tapes, in particular also be cast on a casting wheel. On this way, the intermetallic phases succeed in train defined grain size. The grain size should be in in any case less than 80 µm, preferably less than 40 µm and particularly preferably less than 20 µm be. The best results are achieved when the Dimension or the cooling rate so high is that grain sizes of less than 5 µm result.
Zur Herstellung der Werkstücke oder Halbzeuge größerer Abmessung wird nun auf erfindungsgemäße Weise das im ersten Schritt erhaltene Vormaterial erneut auf Temperaturen erwärmt, bei denen die Aluminium-Matrix wenigstens teilweise bzw. soweit erschmolzen wird, die Ausscheidungskristalle der intermetallischen Phasen jedoch im Wesentlichen fest bleiben. Es wird dann ein Werkstück oder ein Halbzeug mit gegenüber der Abmessung des Vormaterials größerer Abmessung geformt, ohne dass die Ausscheidungskristalle ihre Feinkörnigkeit verlieren. Sie liegen also sowohl in dem Vormaterial als auch im fertigen Werkstück oder Halbzeug in derselben homogenen und feinkörnigen Verteilung vor. Ein auf diese erfindungsgemäße Weise hergestelltes Halbzeug kann dann einem Strangpressprozess oder einem Walzprozess unterworfen werden, ohne dass die Ausscheidungskristalle der intermetallischen Phasen zerstört werden. Dies ist auf ihre Feinkörnigkeit zurückzuführen.For the production of workpieces or semi-finished products larger Dimension is now the first in the manner according to the invention Step obtained raw material again at temperatures heated, in which the aluminum matrix at least partially or to the extent that is melted Precipitation crystals of the intermetallic phases, however stay essentially solid. It then becomes a workpiece or a semi-finished product with compared to the dimension of the Material of larger dimensions shaped without the Precipitation crystals lose their fine grain. she therefore lie both in the primary material and in the finished one Workpiece or semi-finished product in the same homogeneous and fine-grained distribution. One according to this invention Semi-finished products produced in this way can then be Extruded process or subjected to a rolling process without the precipitation crystals of the intermetallic phases are destroyed. This is due to their Attributed to fine grain.
Bei der Auswahl des die intermetallische Phasen bildenden Zusatzes oder der Zusätze erweist es sich als vorteilhaft, solche Legierungselemente zu wählen, welche intermetallische Phasen bilden,deren Schmelztemperatur möglichst hoch und deren Löslichkeit in der wieder aufgeschmolzenen Aluminium-Schmelze möglichst gering ist. Bei den intermetallischen Phasen handelt es sich bevorzugtermaßen um Aluminide, es könnten aber grundsätzlich auch Verbindungen der Legierungselemente sein. Bei den Legierungselementen zur Ausbildung von Aluminiden als intermetallische Phasen handelt es sich bevorzugt um Titan und Zirkon, welche zu Al3Ti bzw. Al3Zr auskristallisieren. Im Falle des Zusatzes von Titan ist die Wiederaufschmelztemperatur im zweiten Schritt des erfindungsgemäßen Verfahrens etwa 800° Celsius. Bei dieser Temperatur ist die Aluminium-Matrix bereits wieder flüssig, das gebildete Titanaluminid, Al3Ti, mit einem Schmelzpunkt von 1460° Celsius ist jedoch noch fest. Aufgrund der geringen Löslichkeit des Al3Ti in der Aluminium-Schmelze von etwa 0,4 % bleiben die Ausscheidungskristalle auch weitestgehend erhalten und werden nicht gelöst. Die Temperatur, auf die das Vormaterial im zweiten Schritt des erfindungsgemäßen Verfahrens wieder aufgewärmt wird, muß deutlich unter der Schmelztemperatur der betreffenden intermetallischen Phase gehalten werden, sie muß jedoch andererseits so hoch sein, dass ein ausreichender Schmelzenanteil für die sich anschließende Umformung in die gewünschten Abmessungen vorhanden ist. Das hieran anschließende Formen oder Umformen kann durch einfaches Schwerkraft-Gießen aber auch im Druck- oder Schleuderkraftguß erfolgen. Die so hergestellten Halbzeuge mit größeren Abmessungen eignen sich vorzüglich für die Umformung z.B. im Strangpressverfahren, Schmieden, Walzen oder Tixocasting, da die feinkörnigen harten Ausscheidungskristalle bei den Umformvorgängen nicht zerstört werden und eine gleichmäßige Verteilung der verschleißmindernden Phasen erreicht wird.When selecting the additive or additives forming the intermetallic phases, it proves to be advantageous to choose those alloy elements which form intermetallic phases, whose melting temperature is as high as possible and whose solubility in the remelted aluminum melt is as low as possible. The intermetallic phases are preferably aluminides, but in principle it could also be compounds of the alloying elements. The alloying elements for forming aluminides as intermetallic phases are preferably titanium and zircon which crystallize out to form Al 3 Ti and Al 3 Zr. If titanium is added, the remelting temperature in the second step of the method according to the invention is about 800 ° Celsius. The aluminum matrix is already liquid again at this temperature, but the titanium aluminide formed, Al 3 Ti, with a melting point of 1460 ° Celsius is still solid. Due to the low solubility of the Al 3 Ti in the aluminum melt of about 0.4%, the precipitation crystals are largely preserved and are not dissolved. The temperature to which the starting material is reheated in the second step of the process according to the invention must be kept well below the melting temperature of the intermetallic phase in question, but on the other hand it must be so high that a sufficient proportion of melt for the subsequent shaping into the desired dimensions is available. The subsequent shaping or reshaping can be done by simple gravity casting but also in pressure or centrifugal casting. The semi-finished products with larger dimensions that are produced in this way are particularly suitable for forming, for example, in the extrusion process, forging, rolling or tixocasting, since the fine-grained hard precipitation crystals are not destroyed during the forming processes and the wear-reducing phases are evenly distributed.
Zusätzlich zu dem oder den intermetallische Phasen bildenden Zusätzen können solche Zusätze, wie Kupfer, Magnesium, Mangan verwendet werden, welche die Matrixhärte der Legierung erhöhen. Es kann sich darüberhinaus als vorteilhaft erweisen, wenn weitere harte Kristalle, wie z.B. Silizium, in die Aluminium-Matrix eingelagert werden.In addition to the intermetallic phase or phases forming additives such as copper, Magnesium, manganese are used, which is the matrix hardness increase the alloy. It can also prove to be turn out to be advantageous if other hard crystals, such as e.g. Silicon to be embedded in the aluminum matrix.
Weitere Merkmale, Einzelheiten und Vorteile der Erfindung ergeben sich aus den beigefügten Ansprüchen. In der Zeichnung zeigt:
Figur 1- ein Schliffbild eines unter Anwendung des erfindungsgemäßen Verfahrens hergestellten Werkstücks und
Figur 2- ein der
Figur 1 entsprechendes Schliffbild eines in einem einzigen Schritt gegossenen Werkstücks.
- Figure 1
- a micrograph of a workpiece produced using the method according to the invention and
- Figure 2
- a micrograph corresponding to FIG. 1 of a workpiece cast in a single step.
Während im Schliffbild nach Figur 2 größere Aussscheidungskristalle einer Abmessung von 100 µm und mehr zu erkennen sind zeigt das Schliffbild nach Figur 1 ein feinkörniges, homogenes Gefüge einer verschleißarmen Aluminium-Legierung, wobei einer Aluminium-Basislegierung Titan und andere die Matrixhärte erhöhende Zusätze zugegeben wurde. Die dunklen Phasen stellen Ausscheidungskristalle dar. Ausgehend von einer Schmelze von ca. 1500 ° Celsius wurde ein Strang in der Größenordnung von ca. 20 mm Durchmesser gegossen und dabei derart schnell zum Erstarren gebracht, dass Ausscheidungskristalle in der Form von Titanaluminid, Al3Ti, homogen verteilt mit einer Abmessung von weniger als 80 µm gebildet werden. Die gewünschte Korngröße wird über die Strangabmessungen und die Wärmeabfuhrbedingungen eingestellt. Der etwa "fingerdicke" Strangguß wird dann in einem zweiten Verfahrensschritt erneut auf eine Temperatur von etwa 800° Celsius gebracht, bei der die Aluminium-Matrix des Vormaterials wenigstens teilweise erschmolzen wird, so dass ein ausreichender Schmelzenanteil für das Formen oder Gießen eines Werkstücks mit gegenüber der Abmessung des fingerdicken Strangs des Vormaterials größerer Abmessung oder für das Gießen eines Halbzeugs, etwa eines dicken Rugels für einen nachfolgenden Strangpressprozess, vorhanden ist. Da die Wiederaufschmelztemperatur im zweiten Schritt des Verfahrens deutlich unterhalb der Schmelztemperatur des Titanaluminids liegt und ferner die Löslichkeit des Titanaluminids in der Aluminium-Schmelze bei der Wiederaufschmelztemperatur lediglich 0,4 % beträgt, bleiben die feinkörnigen Ausscheidungen des Titanaluminids weitestgehend erhalten und kennzeichnen auch das Gefüge des schlußendlichen Werkstücks oder Halbzeugs.While larger precipitation crystals with a dimension of 100 μm and more can be seen in the micrograph according to FIG. 2, the micrograph according to FIG. 1 shows a fine-grained, homogeneous structure of a low-wear aluminum alloy, titanium and other additives which increase the matrix hardness being added. The dark phases represent precipitation crystals. Starting from a melt of approx. 1500 ° Celsius, a strand in the order of magnitude of approx. 20 mm in diameter was cast and thereby solidified so quickly that precipitation crystals in the form of titanium aluminide, Al 3 Ti, homogeneously distributed with a dimension of less than 80 microns. The desired grain size is set via the strand dimensions and the heat dissipation conditions. The approximately "finger-thick" continuous casting is then brought back to a temperature of approximately 800 ° Celsius in a second process step, at which the aluminum matrix of the primary material is at least partially melted, so that a sufficient amount of melt for molding or casting a workpiece is compared the dimension of the finger-thick strand of the primary material of larger dimension or for the casting of a semi-finished product, such as a thick rug, for a subsequent extrusion process. Since the remelting temperature in the second step of the process is significantly below the melting temperature of the titanium aluminide and furthermore the solubility of the titanium aluminide in the aluminum melt at the remelting temperature is only 0.4%, the fine-grained precipitates of the titanium aluminide are largely retained and also characterize the structure of the final workpiece or semi-finished product.
Claims (15)
- Method for producing workpieces or semi-finished products from a low-wearing aluminium alloy with additives forming intermetallic phases, characterised in that in a first step a melt of the alloy is cast in such a small dimension that such a high rate of cooling is achieved that the resulting precipitation crystals of the intermetallic phases are homogeneously distributed and are precipitated from the melt with a defined particle size, that the precursor-material obtained in the first step is heated to temperatures in the region of the heterogeneous region between aluminium melt and intermetallic phase and the aluminium is melted until the material is free-flowing under gravitational conditions, and in that a workpiece or a semi-finished product is then formed with dimensions larger than the dimensions of the precursor-material.
- Method according to claim 1, characterised in that the small dimension with which the melt is cast in the first step is less than 50 mm.
- Method according to claim 1 or 2, characterised in that the small dimension with which the melt is cast in the first step is less than 20 mm.
- Method according to any of the preceding claims, characterised in that the defined particle size of the precipitation crystals is less than 80 µm.
- Method according to claim 4, characterised in that the defined particle size of the precipitation crystals is less than 40 µm.
- Method according to claim 5, characterised in that the defined particle size of the precipitation crystals is less than 20 µm.
- Method according to at least any one of the preceding claims, characterised in that the intermetallic phases are aluminides.
- Method according to claim 7, characterised in that they are aluminides of which the solubility in the aluminium melt is less than 5%, preferably less than 1% at the remelting temperature of the second step.
- Method according to claim 7, characterised in that the aluminides are Al3Ti or Al3Zr.
- Method according to at least any one of the preceding claims, characterised in that the additive forming intermetallic phases is titanium or a titanium alloy.
- Method according to at least any one of the preceding claims, characterised in that the additive forming intermetallic phases is zircon or a zircon alloy.
- Method according to at least any one of the preceding claims, characterised in that additional additives, such as Cu, Mg, Mn, increasing the matrix hardness of the alloy are used.
- Method according to at least any one of the preceding claims, characterised in that silicon is deposited in the matrix.
- Method according to at least any one of the preceding claims, characterised in that the semi-finished product is brought into the shape of a bar or ball.
- Method according to at least any one of the preceding claims, characterised in that the semi-finished product is shaped by the extrusion or tixocasting process to form a workpiece.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19649015 | 1996-11-27 | ||
| DE19649015A DE19649015A1 (en) | 1996-11-27 | 1996-11-27 | Process for the production of aluminum semi-finished products |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0845542A1 EP0845542A1 (en) | 1998-06-03 |
| EP0845542B1 true EP0845542B1 (en) | 2002-09-25 |
Family
ID=7812854
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP97110712A Expired - Lifetime EP0845542B1 (en) | 1996-11-27 | 1997-07-01 | Process of manufacturing semi-finished products in aluminium |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0845542B1 (en) |
| DE (2) | DE19649015A1 (en) |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5669346A (en) * | 1979-11-07 | 1981-06-10 | Showa Alum Ind Kk | Aluminum alloy for working and its manufacture |
| JPS61117204A (en) * | 1984-11-12 | 1986-06-04 | Honda Motor Co Ltd | High-strength al alloy member for structural purpose |
| IT1229029B (en) * | 1989-04-14 | 1991-07-12 | Polvara Maria Crosti Giovanni | PROCESS FOR THE PRODUCTION OF CAST ALUMINUM ALLOYS IN THE SEMI-LIQUID STATE, AS WELL AS PLANT FOR ITS IMPLEMENTATION. |
| GB2243620B (en) * | 1990-03-27 | 1994-06-29 | Atsugi Unisia Corp | Improvements in and relating to forming aluminium-silicon alloy |
| JPH05148563A (en) * | 1991-07-30 | 1993-06-15 | Nippon Steel Corp | Production of electrolytic capacitor electrode material |
| DE4321640C2 (en) * | 1993-06-30 | 1998-08-06 | Siemens Ag | Process for the directional solidification of a molten metal and casting device for carrying it out |
| JPH07109536A (en) * | 1993-10-12 | 1995-04-25 | Nippon Light Metal Co Ltd | Aluminum alloy for forging and heat treatment therefor |
| JPH07258770A (en) * | 1994-03-18 | 1995-10-09 | Suzuki Motor Corp | Aluminum alloy and its production |
-
1996
- 1996-11-27 DE DE19649015A patent/DE19649015A1/en not_active Withdrawn
-
1997
- 1997-07-01 DE DE59708317T patent/DE59708317D1/en not_active Expired - Lifetime
- 1997-07-01 EP EP97110712A patent/EP0845542B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| DE59708317D1 (en) | 2002-10-31 |
| DE19649015A1 (en) | 1998-05-28 |
| EP0845542A1 (en) | 1998-06-03 |
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