Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/22—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip
  • B22F3/225—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip by injection molding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/22—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

• the invention relates to a method for producing components by metal powder injection molding of metal powder parts coated with binder, with the features of the type described in the preamble of claim 1
• Complex-shaped components in medium and high numbers of pieces have long been required in automotive engineering, in aviation as moving parts and in off-shore applications and also in medical technology, for example for implants. These are complex-shaped components with dimensions that can be up to As a rule, such complexly shaped components are manufactured using machining processes, such as milling, turning and grinding.
• the materials used are, for example, low-alloy, high-alloy or corrosion-resistant steels, high-speed steels, superalloys, alloys with magnetic properties, hard metals and Other materials not listed in question
• Complex component geometries require a high workload, thus increasing the stucco price. Certain complicated structures can only be realized with the help of extreme effort. This applies in particular to thin parts, such as thin axes , which are subject to the risk of damage due to the mechanical stress during milling, turning and grinding of the part.
• Another manufacturing method for producing a complex-shaped component with small dimensions is the use of investment casting.
• investment casting a mold production is required for each component manufactured, the production of which The amount of work required requires investment casting means that complex-shaped components with small and smallest structures that are in the range of centimeters can no longer be reproduced with certainty.
• the surface of the complex-shaped component produced generally reacts due to the temperature of the liquid casting with the wall surface of the casting mold.
• the reaction layer thus created on the surface of the complex-shaped component must, for example, be pickled to produce a flawless surface. This pickling, in turn, means that narrow tolerances can no longer be maintained.
• the mechanical properties of the casting structure are achieved by investment casting are produced, inferior to the mechanical properties, if the complex-shaped component has been produced with the help of forging technology
• complex-shaped components cannot be manufactured using the state-of-the-art processes described, such as milling, turning, grinding, investment casting, spark erosion and electrochemical processing, because of their special requirements on the component geometry, they usually switch to another material or one chooses a different design, in order to nevertheless achieve a production of the complex shaped component.
• thermoplastic used in the injection molding process and / or use thermosetting materials practically, since they did not have sufficient mechanical properties.
• Titanium powder for the production of heavy-duty components, such as used in motor vehicle construction, etc. Titanium is particularly advantageous as a material for complexly shaped components with small dimensions in the field of medical technology, since such components have an especially good biocompatibility as an implant.
• Titanium powder can be used to achieve the required strength values of components with a complex-shaped structure, but, for example, in the safety-relevant areas of machines and implants, there is no safety reserve for the component made from titanium powder with regard to functionality and against irreparable damage in the event of overloading and against breakage
• Complex components made from titanium powder and with the metal powder injection molding process break immediately when the strength limit is reached without prior plastic deformation (cracking), which, however, is not the case in most cases
• This essential disadvantage of the complex-shaped components produced from titanium powder according to the prior art essentially results from the fact that, during the production of these components, considerable amounts of contaminants, such as oxygen, carbon, nitrogen and the like, are taken up in the material of the titanium component Complex molded components made from titanium powder do not achieve the properties of the same component when the metal powder injection molding process is used if it has been manufactured by the forging process
• the invention is therefore based on the object of providing an inexpensive method suitable for mass production for the production of complex-shaped components, which in particular enables the sintered component to have a safety reserve against inoperability and against irreparable damage in the event of overloading and against breakage, which minimizes allows the inclusion of contaminants in the material of the components during the manufacture of the components until completion, which for the prefabricated component has a homogeneous structure, extremely high reproducibility and dimensional accuracy, which avoids post-processing of the manufactured components, which has a low surface roughness of the finished one Component enables, and this excludes a distortion of the components during the production of the complex shaped
• the advantages of the invention lie in particular in that some of the sections of the method according to the invention for the production of complex-shaped components take place while strictly observing a high-purity protective atmosphere consisting of protective gas and / or air exclusion and / or vacuum. This prevents that during manufacture - process of the complex shaped components contaminants with respect to the given performance data of the component can no longer be tolerated by the component.
• These individual manufacturing sections are, however, partly subdivided into subsections, whereby these subsections also contribute to the inclusion of contaminants in the material the component is always fed to a minimum, such as the metal powder parts of the selected titanium alloy and the constituents of the binder are selected in their composition such that each individual material constituent in its initial state already has the property of being low in contaminants Titanium alloy and the binder, the proportion of undesirable contaminants is set to the lowest possible base value, so that there is an inevitable increase in the amount of contamination during the process Cleaning substances of the material of the component in the final sum corresponding to the selected low basic contamination of the components of the titanium alloy and the binder are reduced
• the production of the metal powder parts and the mixing of the metal powder parts with the binder components for feedstock production take place under the influence of high-purity protective gas, such as argon
• high-purity protective gas such as argon
• the sintering itself is carried out under a vacuum and the debinding is carried out in a commercial debinding bath, for example with hexane and thus with the exclusion of the presence of air and thus of oxygen, carbon, nitrogen and the like as contaminants
• Each individual section of the manufacturing process of the complex-shaped components is subject to the goal of achieving the least possible accumulation of contaminants in each manufacturing step, as well as when the metal powder parts were produced in accordance with the invention.
• a titanium alloy was selected for the high-quality stressing of the components produced, which has the composition T ⁇ -6Al-7Nb.
• the metal powder parts of this titanium alloy which are low in contaminants, can be produced by two processes, namely the electrode induction melting guiding gas atomization process or the plasma melting induction guiding gas atomization process.
• the metal powder parts for the titanium alloy mentioned are produced by means of an atomizing system with argon inert gas atomization, in which the metal powder parts which are depleted of inert gas are collected in the powder can flanged gas-tight to the atomizing system.
• the powder can itself is gas-tight closable and is incorporated into a glove box system, which in turn is operated with argon gas, so that in the manufacture of the metal powder parts an absolutely small increase in contaminants such as oxygen, carbon, nitrogen, etc.
• the rest of the entire mixture of binder components consists of binder components that react to higher melting, decomposition and / or evaporation temperatures compared to the low-melting binder components
• Metal powder fractions of the titanium alloy are coated with binder components made of thermoplastic or thermoset polymers, with thermo-gelling substances, with waxes or surface-active substances or mixtures obtained therefrom.
• a special binder has been selected for the production of the components according to the invention, which is used to reduce the entry of contaminants such as oxygen and Reduction of the residual binder in the component contributes
• a further procedural measure in the production of highly complex components consists in the fact that during the sintering these components must not form a connection with their base during shrinking and should not be changed by contaminants which separate the base on which the components lie during sintering. the same conditions and prerequisites apply to the base for hot isostatic pressing, which can still be carried out for the components after sintering.
• the sinter base for the components is therefore such explained that while the sintering of the components is carried out, the free slidability of the surface of the sintered base for the overlying components remains unchanged, which can be achieved, for example, by designing the surface of the sintered base with a material d he components of reduction-resistant material such as ceramic oxides happen at the same time, the material of the surface of the sintered base is selected so that the material does not emit contaminants at the sintering temperature.
• This configuration of the sintered base is a particular advantage of the invention in order to avoid that the complex components are involved often very minimal structure on the sintered base and also during hot isostatic pressing do not warp or break by sticking to the surface and are not contaminated by contaminants with the respective base
• Another advantage of the present invention is further provided by the selected manufacturing process of metal powder injection molding, in which the mixing of the metal powder parts with the binder components for feedstock production and also the metal molding of the feedstock in the injection molding machine take place at low temperatures, so that no reaction of the feedstock or Binder and metal parts of the feedstock with the mixer itself or, in particular, not with the injection mold in the injection molding machine, so that there are no surfaces on the complex-shaped components which react with the mold or with device parts and therefore do not need to be post-treated, that is that the surface is already in perfect condition, which enables extremely high reproducibility and dimensional accuracy and thus a near-net-shape production of a high-strength component by selecting a titanium alloy for production the metal powder injection molding process for complex
• 1 is a diagram of a basic representation of the method for producing complex shaped components with the metal powder injection molding method
• Fig. 2 shows the reproduction of a tension rod, which is made by the metal powder injection molding technique, before and after a tensile test and
• FIG. 3 shows in table form a compilation of measurement results of samples which were subjected to a tensile test, in particular with indication of the yield strength, the tensile strength and the elongation
• Figure 1 in the form of a diagram is only sketchy and in partial representation, the manufacture of a complex shaped component from the manufacture of the metal powder parts through the feedstock manufacture, the metal molding, the debinding and the sintering with the finished component is shown in Figure 1, 2 and also in the Results in Figure 3 was deliberately dispensed with the representation of a complex shaped component in order to require clarity and to be able to achieve clear measurement results.
• Complex shaped components are, however, for their application in motor vehicle construction, aviation, off-shore applications and in Medical technology, for example in the form of implants required.
• the metal powder parts as the material for shaping components according to the invention can be produced in different ways. Powder can be used that has been produced by mechanical alloying or mechanical comminution he composition of individual titanium alloy components should be selected in such a way that each individual material component in its initial state already has the property of being low in impurities. The required purity of individual material components is based on the requirements placed on the finished end product component when it is used The individual material constituent of the metal powder parts must therefore already have the material properties required for the component to be produced. While the direct powder mixture was described above as the first possibility for producing metal powder parts, the exemplary embodiment in FIG. 1 assumes that pre-alloyed powder is used, for example in the form of a powder Finished alloy made of a rod.
• This finished alloy can also be used to carry out metal powder parts for the production of complex components or a test specimen namely in an atomization plant by means of argon inert gas atomization.
• a atomization plant was used which was specially designed for the production of high-purity titanium alloy powder.
• the atomization of the titanium alloy powder pre-alloyed in a finished alloy takes place under strict compliance with a high-purity protective atmosphere made of protective gas such as argon thereby and through Special design of the atomizing system keeps the absorption of contaminants such as carbon, oxygen and nitrogen very low during the atomization process.
• the system used by the applicants has a carbon and oxygen content of the titanium alloy powder with carbon 0.01% by weight, oxygen 0 , 21% by weight, these values being only slightly above the values that each individual material component already had in the initial state, namely 0.01% by weight for carbon and 0.2% by weight for oxygen
• the inert Metal powder parts are collected in a powder can flanged gas-tight to the evaporation plant.
• This powder can itself is designed to be gas-tight and the powder can is then fed into a glove box system, which in turn is operated with the protective gas argon.
• the powder components must be less contaminated than the end product, since in the manufacturing process of the component there is one Minimization of the contaminants absorbed into the component can be carried out, however a complete avoidance of the absorption of contaminants during the manufacturing process of the component It is practically impossible To achieve the goal of high-purity metal powder parts, two different processes were used to produce metal powder parts for the titanium alloy.
• the electrode induction melting gas atomization process was used, and the plasma melting induction guiding gas atomization process was different Results with regard to the total amount of pollutants in the manufacture of the metal powder parts are also caused by the fact that when using a pre-alloyed powder in the form of a finished alloyed rod according to the DIN standard, the oxygen content is already specified in the finished product at 2000 ⁇ g / g, with reference to the specified amount of Oxygen contamination also add up the percent by weight of oxygen contamination and of course other contaminants that arise during the manufacture of the metal powder parts due to the contamination contained in the finished alloy, which is permitted according to the DIN standard Contaminants, it is advantageous to put together the individual material constituents of the titanium alloy in order to achieve a better result in the initial state through special care in the selection and treatment of the individual constituents, ie a result that already minimizes, for example, the oxygen concentration during the manufacture of the metal powder parts enabled in the initial state
• metal powder parts When using inert gas atomization for the production of metal powder parts, metal powder parts are formed in a pronounced spherical shape.
• the spherical shape is advantageous for sintering, because a high packing density of the metal powder parts can be achieved due to the spherical shape of the powder and thus a low residual porosity of the sintered, complex component is achieved
• the amount of metal powder produced is then sieved by means of a sieve chain according to the particle size of the metal powder parts.
• the use of metal powder parts with a particle size of ⁇ 100 ⁇ m is particularly suitable for the production of the complex-shaped components
• Favorable results are achieved if a particle size ⁇ 45 ⁇ m is preferably used.
• the resulting material loss in the production of metal powder is about 70 to 75% of the metal powder parts produced when using metal powder parts with a particle size ⁇ 45 ⁇ m, in contrast to the often 90% material loss in the production of the complex-shaped components by means of machining processes.
• the sieved metal powder parts with a particle size> 45 ⁇ m can be used for other purposes, so that the material loss can be reduced even more.
• the surface roughness of the finished, complex-shaped component depends on the powder size and is typical when using metal powder parts with a particle size of ⁇ 45 ⁇ m 1 ⁇ m in general This means that the surface of the finished, complex-shaped component must always be used without reworking
• the titanium alloy in rod form 1 is shown by way of example, which is processed into metal powder parts 2 by means of inert gas evaporation, wherein it has already been described that this is only one possibility of producing the metal powder parts.
• the feedstock production follows in FIG. 1 b), ie the mixing of the metal powder parts 2 with the binder 3 in a kneader 4 to the feedstock 5
• the metal injection molding of the feedstock takes place by means of an injection molding machine 6, which is only schematically indicated here in block form and to which the feedstock 5 is fed and below Pressure is injected into the injection mold 7 into the shape of the component 8.
• the green body of the component 8 thus produced is partially released in the debinding in FIG.
• the binder components are thermoplastic or thermosetting polymers, thermogelling substances, waxes or surface-active substances or mixtures obtained therefrom. Binder components can be added thereby polyamides, polyoxymethylene, polycarbonate, styrene-acrylonitrile copolymers, polyimide, natural waxes and oils, thermosets, cyanates, polypropylenes, polyacetates, polyethylenes, ethylene-vinyl-acetates, polyvinyl alcohols, polyvinyl l-chlorides, polystyrene, polymethyl Methacrylates, anilines, water, mineralols, agar, glycenn, polyvinyl-butyryl, polybutyl methacrylates, cellulose, oleic phthalates, paraffin waxes, camauba wax, ammonium polyacrylates, digyl-cad stearates and olates, glyceryl monostearates, Isopropyl titanate, lithium
• lubricants must also be added to prevent the binder components and the metal powder parts from sticking together It must be ensured with the kneader 4 for a sufficiently homogeneous mixing without the constituents clumping.
• the binder 3 must also be in its components are selected so that no decomposition of the binder takes place during metal injection molding.
• the binder must also be very easily removed from the component produced by means of metal powder injection molding, since it is only used for temporary cohesion the metal powder constituents after the metal mold spraying.
• the binder which always consists of several constituents, must be designed in such a way that each individual material constituent in its initial state already has the property of being low in contaminants such as oxygen, nitrogen and carbon. Quite essential for the production of a complex Shaped component is also in relation to the binder and its components that they help to maintain the required material properties of the component until the component is finished and not to change it by additional absorption of contaminants.
• the kneader and / or the kneading chamber is preferably included high-purity protective gas, such as argon, to prevent contamination of the two components of the feedstock, for example with oxygen and nitrogen from the air.
• high-purity protective gas such as argon
• the binder forms a shell around each individual metal powder part
• shear processes must ensure that every metal powder part is covered with binder. This is usually done in so-called Z-blade mixers or also in planetary mixers.
• the feedstock usually contains about 30 to 40 vol% binder
• the mixing of the metal powder parts of the titanium alloy and the constituents of the binder in the feedstock manufacture is carried out in a low temperature range.
• the temperature range in the feedstock manufacture is between 50 degrees and 200 degrees Celsius.
• Provide settlement and / or evaporation temperature Those binder constituents which have a low melting, decomposition and / or evaporation temperature predominate compared to the proportion of binder constituents in the mixture which have a higher different melting, decomposition and / or evaporation temperature Poor binder contaminants, the individual components of which already have the property of being low in contaminants in the initial state, consist of polyethylene, stearic acid, paraffin and camauba wax
• the metal injection molding of the component 8 in an injection molding machine 6 in the injection mold 7 follows.
• the injection molding machines customary in the plastics industry are generally used for the metal injection molding.
• the feedstock is generally pelletized and, if necessary, into the pellet Injection molding machine introduced
• the precise parameters for metal injection molding such as pressure and temperature, depend on the geometry of the complex-shaped component and the flow properties of the feedstock.
• the pressure is in the range from 30 to 50 bar.
• Metal injection molding has the advantages of an inexpensive and excellent reproducibility To enable complex shaped components with small tolerances and is particularly suitable for medium to high numbers of pieces.
• the metal injection molding of the complex-shaped component for the production of the green body takes place in a low temperature range.
• This temperature range lies between 60 degrees and 200 degrees Celsius for metal molding.
• This low temperature range makes it possible to prevent the surface of the sprayed green body from being selected when selecting the binder components the injection molding machine reacts with the surface of the injection mold 7, which is why the surface is smooth and does not have to be reworked after the component has been finished.
• This also applies, as already described, to the manufacturing process in feedstock production which is in a similar low temperature range and which is between Moving 50 degrees and 200 degrees Celsius
• it can be a A ⁇ 34332IFAMneu2 doc there is no reaction of the surface of the kneader with the resulting feedstock and therefore there are no disruptions in production.
• Partial debinding is carried out first, for example by thermal expulsion or in a commercial debinding bath, which is carried out, for example, with hexane in the absence of air at a slightly elevated temperature in the order of 40 degrees Celsius for a few hours. Large portions of the binder content are removed at a slightly elevated temperature with the aid of the solvent. This heating must be carried out very carefully done to avoid warping and destruction of the complex shaped component. That is why the binder is composed of various components that evaporate at different temperatures. During partial debinding under the influence of the solvent hexane, about 75% of the binder is removed from the green ling, which is then called the partially debonded component Braunling.
• the solvent hexane ensures that the debinding takes place with the complete exclusion of air and also of contaminants such as carbon, oxygen, nitrogen and thus prevents an accumulation of contaminants in the sprayed component. Further removal of the residual binder, which can only be removed at a higher temperature and has hitherto prevented the component from being kept apart, takes place by thermal decomposition.
• the thermal decomposition preferably takes place in a high vacuum, but can also take place in a pure protective gas atmosphere such as argon Drying in argon gas instead
• argon Drying in argon gas instead The handling of the sprayed components in the form of a green body and the partially debindered components in the form of a brown body must be carried out carefully to avoid warping or breakage.
• the next step in the completion of the complex-shaped components is the sintering, as can be seen from FIG. 1 e).
• the brown part of the component undergoes a heat treatment in which the individual metal powder parts obtain metallurgical contacts in the form of a welding diffusion with one another.
• a successful sintering process at Ti - Tan alloys and the achievement of a perfect material property of the component can only be achieved by avoiding the inclusion of additional contaminants such as oxygen, carbon and nitrogen during the sintering process in the metal powder.
• the atmosphere of the chamber of the sintering furnace with an excellent vacuum of the order of ⁇ 10 Have 5 mbar the high temperatures when sintering are unfavorable for maintaining good material properties, since at these high temperatures a particularly good absorption of impurities takes place in the metal powder parts.
• the temperature interval during sintering is between 1,100 degrees and 1,400 degrees Celsius. Tests during production have shown that preferably the temperature of 1300 degrees Celsius provides an optimal result with regard to the properties of the manufactured component.
• a heating rate adapted to the evaporation rate of the residual binder still contained in the brown compact of the component, e.g. B 5 K / min is selected, as a result of which the residual binder is expelled thermally during the heating process in the sintering chamber.
• the complex-shaped component produced after sintering has a density close to the theoretical density, namely at 96%.
• the mechanis The properties of the finished component are very similar to those of forged material with a comparable composition
• the sintered underlay plays an important role in the flawless manufacture of the complexly shaped components.
• the sintered underlay for the complexly shaped components is therefore designed in such a way that the free sliding of the surface of the sintered underlay for the overlying components remains unchanged during the sintering of the components
• the material of the sintered base is therefore selected so that at the sintering temperature the surface of the sintered base consists of material that is resistant to the material of the components, as is the case, for example, with ceramic oxides.
• a material of the sintered base is used that is at the sintering temperature does not emit contaminants This selection of the materials of the sintered base causes a delay in the construction when storing the complex shaped components on the sintered base and in the shrinking process occurring during the sintering parts and possible breakage avoided
• a subsequent hot isostatic pressing treatment can be used to bring the residual porosity of the sintered part to zero in order to get all the theoretically possible mechanical properties out of the material of the component.
• the sintered components are placed in a high-purity protective gas such as argon given chamber and hot isostatically pressed for a few hours at a temperature of about 850 degrees Celsius and 2000 bar gas pressure.
• the high-purity protective gas argon is necessary because at these high temperatures the tendency of the titanium alloy to absorb foreign substances is high, but this must be prevented For the same reason, care should also be taken with the material of the contact surface for the components in isostatic pressing that this support maintains the free gliding ability through the formation of a suitable material such as ceramic oxides during the pressing and that the material of the contact surface does not release any contaminants into the chamber and to the components at the temperature of the isostatic pressing.
• the hot isostatic pressing process is only carried out if either Material inside the components must not have porosity or if the highest possible strengths with a density of 100% and the best possible ductility are required for the respective application and the additional costs incurred are therefore accepted
• the titanium alloy T ⁇ -6AI-7Nb has also been used for other purposes so far, but could not be used in a metal powder injection molding process without the elasticity being lost due to the absorption of contaminants during the manufacturing process, so that the end product obtained has a safety margin of the sintered component in terms of functionality and against irreparable damage in the event of overloading of the component and against breakage in the prior art was missing.
• the component manufactured with titanium according to the prior art may have high strength, but does not behave like a metal in terms of ductility , It is not elastically but plastically deformable Only through the combination of the features of the selection of the titanium
• FIG. 2 Only by the combination of these features the ductility of the tensile rod shown in FIG. 2 is maintained until the completion of the production after sintering.
• FIG. 2a the tensile rod 8 can be seen after completion.
• FIG. 2b clearly shows that the tension rod produced by sintering behaved like normal metal in that it had plastically deformed before breaking apart, that is to say it had become longer before it broke apart.
• FIG. 3 shows the measurement results of mechanical tests in the manufacture of tensile specimens of the tensile rod 8.
• the sintering temperature of 1250 degrees Celsius and 1300 degrees Celsius and the surface treatment were ground or not ground.
• Some samples of the tensile rod were additionally varied a hot isostatic process was connected in order to achieve a 100% density, in the other sample the density was around 96%.
• FIG. 3 tensile samples of tensile bars are summarized which were subjected to the following different treatment
• the oxygen content is approx. 0.25% by weight, the carbon content is approx. 0.06%.
• the micrographs showed a homogeneous, fine-lamellar microstructure of ⁇ and ⁇ phase with an average grain size of approximately 150 ⁇ m.
• the pores have a maximum size of 10 ⁇ m, in the case of the samples subjected to a hot isostatic pressing process, there are no pores.
• the surface treatment is not a polish, but only a cut, which eliminates any surface notches should Since the material is ductile, the influence of the surface quality should not play a major role in the experiments
• the structure in the case of the forged material is fine-grained globular, while the tension rod material produced according to the invention has a fine lamellar structure.
• the carbon content is in each case approximately 0.06% by weight, the increase compared to the starting alloy is approximately 0.05% by weight.
• the oxygen content increases by a maximum of 0.06% by weight, the starting alloy already had 0.19% by weight.
• the results of the tensile tests on tensile rod 8 can be interpreted as follows. All samples show excellent strength. Except for the case of the heat-treated sample, the measured value is Elongation in the tension rod samples produced according to the invention is significantly higher than in the forged version The samples sintered at 1300 degrees Celsius show somewhat better results on average than the tension bar sintered at 1250 degrees Celsius.
• Titanium alloy in rod form

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• 1999
  • 1999-07-28 WO PCT/DE1999/002343 patent/WO2000006327A2/fr active IP Right Grant
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