DE102018212480A1 - Additive manufacturing process with selective irradiation and simultaneous application as well as heat treatment - Google Patents

Abstract

An additive manufacturing method for components (10) to be used in the hot gas path of turbomachines is specified. The method comprises the selective irradiation of a base material (P) for the component (10) with a laser or electron beam (B1) at the same time as (i) the application of new base material (P) for the construction of the component (10), and (ii ) a heat treatment, for example by induction heating (120), of an already irradiated material (S) for the component (10), the selective irradiation and the heat treatment being coordinated in such a way that a structure (S) is directed for the component (10) stiffens. Furthermore, a correspondingly manufactured component and a corresponding device are specified.

Description

The present invention relates to an additive manufacturing method, in particular for components to be used in the hot gas path of turbomachines such as gas turbines.
The components mentioned are preferably made from a superalloy, in particular from a nickel- or cobalt-based superalloy. The alloy can be precipitation hardened or precipitation hardenable.

The method presented is intended, in particular, to achieve an epitaxial material structure and / or a directionally solidified material structure for the component, for example in stem-crystalline or single-crystalline form.

In gas turbines, thermal energy and / or flow energy is generated by burning a fuel, e.g. a gas, hot gas generated converted into kinetic energy (rotational energy) of a shaft rotor. For this purpose, a flow channel is formed in the gas turbine, in the axial direction of which the rotor or a shaft is mounted.

The turbine blades expediently protrude into the flow channel. If a hot gas flows through the flow channel, the blades are subjected to a force which is converted into a torque acting on the shaft which drives the turbine rotor, the rotational energy e.g. can be used to operate a generator.

Modern gas turbines are subject to constant improvement in order to increase their efficiency. However, this leads, among other things, to ever higher temperatures in the hot gas path. The metallic materials for blades, especially in the first stages, are constantly being improved in terms of their strength at high temperatures (creep load, thermomechanical fatigue).

Generative or additive manufacturing is becoming increasingly interesting due to its disruptive potential for industry, and also for the serial production of the above-mentioned turbine components, such as turbine blades or burner components. Additive manufacturing processes include, for example, as a powder bed process, selective laser melting (SLM) or laser sintering (SLS), or electron beam melting (EBM).

A method for selective laser melting is known for example from EP 2 601 006 B1 ,

Additive manufacturing processes (English: "additive manufacturing") have also proven to be particularly advantageous for complex or complex or filigree designed components, such as labyrinthine structures, cooling structures and / or lightweight structures. Additive manufacturing through a particularly short chain of process steps is particularly advantageous, since a manufacturing or manufacturing step of a component can take place on the basis of a corresponding CAD file and the selection of corresponding manufacturing parameters.

Often, however, the material or structural properties of additively manufactured components or component sections are inferior to those of conventionally manufactured components or structures. The reasons for this are often the large temperature gradients involved in the additive "welding processes", which make the structures susceptible to hot or solidification cracks. In terms of process technology, it has not yet been possible to additively build up single-crystalline, stem-crystalline or directionally solidified structures.

It is therefore an object of the present invention to provide means by which the directional, dendritic or epitaxial solidification of material is made possible by means of additive manufacturing. In addition to the known advantages of additive technology in relation to the degrees of design freedom, the described method is also intended to improve the structure of the components and / or to simplify post-processing or to make it completely unnecessary.

This object is solved by the subject matter of the independent claims. Advantageous refinements are the subject of the dependent claims.

One aspect of the present invention relates to an additive manufacturing method for components to be used, for example in the hot gas path of turbomachines such as gas turbines.

The method described should not be limited to the additive manufacturing of components for turbomachines. Rather, the method presented is intended to be restricted only by its suitability for the manufacture of the components mentioned, although it can of course also be suitable for neighboring technology fields such as, for example, the automotive or aviation sector or machine manufacture in general.

The method comprises the selective irradiation of a base material for the component with a laser or electron beam. The selective irradiation with a laser beam is preferably carried out in such a way that a previously applied base material, for example powder, on a production surface or forming it, is selectively exposed to a laser beam.

The production area can accordingly be formed by the base material, by a construction platform as a substrate and / or by an already solidified or built structure.

Simultaneously with the selective irradiation, the method comprises the application of a base material, in particular new base material, that is to say one that has not yet been applied, for the construction of the component and a heat treatment, for example by induction heating, for example a previously irradiated material for the component or part of the component Component or its structure.

The selective irradiation and the heat treatment are coordinated in accordance with the method in such a way that a structure for the component is solidified or solidified in a directed manner, preferably through epitaxial growth or epitaxial structure. The heat treatment mentioned can be, for example, a heat treatment.

In the present case, the expression “at the same time” is intended to mean that the method steps described in this connection relate to the additive structure of the structure as a whole and preferably not to individual layers. Strictly speaking, the application of new base material and the selective irradiation of precisely this (newly applied) “material dose” does not take place at the same time. Rather, the method describes a continuous process, but material for the structure to be built or the component is simultaneously processed, for example, in different areas of the production area or the component, that is to say applied and is selectively irradiated in another part, for example. Another part, for example an already solidified structure of the component, can still be treated with heat at the same time.

The expression “matched” is intended to mean, for example, that heat treatment and a corresponding selection of a large number of parameters are preferably selected such that a corresponding epitaxial or directional solidification takes place. The aforementioned coordination can relate, for example, to the spatial design of a heating device (induction heating) and its operation.

Using the described method, a generative manufacturing process can be selected on one side for the components mentioned, which enables the generative construction of particularly complex geometries.

On the other hand, the structural disadvantages that are usually associated with additive manufacturing can be avoided by the described method. In particular, a particularly advantageous fine, dendritic microstructure can be achieved, which is formed on the basis of the large temperature gradients inherent in the additive processes. Furthermore, a more homogeneous structure, in particular with smaller interdendritic areas, can be achieved compared to known additive processes. Accordingly, subsequent heat treatment, for example solution annealing that takes place outside the device or system or stress-relaxing heating can be dispensed with, or these treatments can at least be restricted.

In one embodiment, a building platform on which the structure for the component is built is successively lowered during the selective irradiation and during the heat treatment, i.e. in particular, for example, to other system components of a corresponding additive manufacturing system. The above-mentioned production area preferably remains in the same vertical position (z direction). This is preferably made possible by the fact that the building platform is lowered only by a small amount, for example its layer thickness corresponding to an applied and / or solidified component layer.

In one embodiment, the application of new base material is carried out from above onto the production area using an application device. This configuration enables, in particular, a coherent and / or continuous implementation of the method, it being possible, for example, for the method steps of selective irradiation, application and heat treatment to be carried out at least partially simultaneously and without unnecessary downtimes.

In one embodiment, new base material is applied with the application device by means of or via a rotational movement of the application device. This configuration is preferred. Either the application device can be rotated relative to other system parts, for example.

Alternatively, those parts of the plant which comprise or define the production area can be rotated or rotated relative to the application device. The design of the application device or the method step of application by means of a rotary movement offers the advantage that the application of new base material or powder, as well as the additive structure as a whole, can be carried out continuously and / or along a screw movement, and thus the advantages of known ones Crystal pulling processes like that Bridgeman processes can be used at least partially.

In one configuration, a temperature gradient is formed as part of the heat treatment below the production area. This can be done, for example, by a heating device which can be regulated and / or controlled vertically in stages.

In one embodiment, a higher temperature is set near the production surface and - with increasing distance from it - a temperature that decreases or decreases, for example, gradually and / or monotonously (relative to the temperature mentioned).

This configuration (s) prevents large temperature gradients, for example along the vertical direction, and thus prevents the likelihood of hot or solidification cracks occurring during the construction of the structure.

In one configuration, the structure for the component is built up epitaxially and / or by directional solidification. This configuration in particular enables a homogeneous and / or defect-free or defect-free crystal or material structure to be achieved, which can be subjected to a considerably higher load during operation of the component than, for example, in the case of known additively constructed structures.

In one embodiment, the base material or powder is preheated before the selective irradiation with a laser or electron beam. Preheating is preferably carried out by means of a laser beam. Preheating enables further degrees of freedom in heat management or the control of the temperatures that develop during the process. Just like the heat treatment described, preheating can also efficiently and expediently reduce the temperature gradients that occur during the additive welding process and thus advantageously reduce the risk of hot and / or solidification cracks.

Another aspect of the present invention relates to a component which can be produced and / or produced according to the described method. The component furthermore comprises a directionally solidified and / or single-crystalline crystal structure with traces of welding, which show at least largely epitaxial crystal growth of individual layers or regions. The welding traces mentioned can be welding beads or solidified contours of melting baths.

Another aspect of the present invention relates to a device for the additive manufacturing of the component as described above. The device comprises an application device or a storage container for applying base material to the described production area.

The device further comprises an inductive heating device for zone melting or forming a temperature gradient, below the production area.

In one embodiment, the device is part of an additive manufacturing system, a retrofit kit for it or the device itself represents the manufacturing system.

In one embodiment, the inductive heating device is set up in a manner similar to a device for “pulling” or building single crystals according to the so-called Bridgman-Stockbarger method. With this configuration, the advantages of this crystal pulling method, in particular with regard to the achievable crystal order and / or material or crystal structure, can be exploited in the present case.

In one configuration, the device comprises a lowerable construction platform, the device furthermore having temperature sensors, for example set up along a construction direction.

Furthermore, the construction platform and the application device are set up, for example movable relative to one another, in particular rotatable.

In one configuration, the device comprises a first irradiation device, in particular a first laser scanning system, for melting or remelting the base material.

In one configuration, the device comprises a second irradiation device, in particular a second laser scanning system, for preheating the base material.

In one embodiment, the construction platform is set up to form a seed for the structure of the component. In the present case, “crystallization seed” can mean any agent that can bring about the formation of an advantageous crystallographic orientation.

Refinements, features and / or advantages, which in the present case relate to the method or the component, can also relate to the device or vice versa.

Further features, properties and advantages of the present invention are explained in more detail below on the basis of exemplary embodiments with reference to the attached figures. All described so far and below Features are advantageous both individually and in combination with one another. It is understood that other embodiments may be used and structural or logical changes may be made without departing from the scope of the present invention. The following description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

The term "or", "or" and "and / or" used here when used in a series of two or more elements means that each of the elements listed can be used alone, or any combination of two or more of the listed items may be used.

• 1 zeigt eine schematische Schnittansicht einer erfindungsgemäßen Vorrichtung.
• 2 zeigt eine schematische Aufsicht auf eine Herstellungsfläche.
• 3 zeigt ein schematisches Flussdiagramm mit angedeuteten Verfahrensschritten des vorgestellten Verfahrens.

Further details of the invention are described below with reference to the figures.

• 1 shows a schematic sectional view of a device according to the invention.
• 2 shows a schematic plan view of a manufacturing area.
• 3 shows a schematic flow diagram with indicated method steps of the presented method.

In the exemplary embodiments and figures, elements that are the same or have the same effect can each be provided with the same reference symbols. The elements shown and their size relationships with one another are fundamentally not to be regarded as true to scale; rather, individual elements can be shown in an exaggeratedly thick or large size for better illustration and / or for better understanding.

1 shows schematically a simplified sectional view of a device according to the invention 100 , The device 100 is preferably part, for example as a retrofit, of an additive manufacturing system (not explicitly identified in the present case) for a component 10 , Alternatively, the device 100 also represent the facility.

With the component 10 it is preferably a component which is used in the hot gas path of a turbomachine, for example a gas turbine. In particular, the component can be a moving or guide vane, a segment or ring segment, a burner part or a burner tip, a frame, a shield, a heat shield, a nozzle, seal, a filter, a mouth or lance, a resonator, stamp or a swirler designate, or a corresponding transition, use, or a corresponding retrofit part.

The device 100 is preferably a device suitable for powder bed-based additive component production, for example for selective laser sintering, selective laser melting or electron beam melting.

The device 100 includes an applicator 110 for applying base material or powder P to a production area HF. As in 1 the base material P can be recognized by the application device 110 applied from above onto the production area HF, preferably by trickling and / or knife coating. The representation of the 1 is only shown schematically in this regard. However, it can be seen that the application device 110 a reservoir 111 for basic material P and a guide sieve 112 for the powder particles or similar auxiliaries, for example agents which enable homogeneous powder application over the entire production area HF.

Furthermore, the application device 110 Movable to the manufacturing area HF, in particular rotatable. The application device is preferred 110 relative to the rest of 1 shown parts of the device 100 or system rotates during the powder application movement. This is indicated by the curved arrow and the rotation angle α shown.

According to this configuration, the powder P for example, not necessarily in individual layers (cf. S1 . S2 ) by straight-line application from right to left, but in particular in a kind of screw movement and / or quasi-continuously during the assembly process on the production surface HF applied and irradiated or melted.

The manufacturing area HF is in the representation of the 1 partly through layers that have already been built up beforehand (see reference numerals S1 . S2 ) the component structure S for the component 10 and partly through base material P educated. The component is within an installation space that is not further identified 10 accordingly still below the manufacturing area HF arranged.

The device 100 also includes an inductive heating device 120 for zone melting or forming a temperature gradient below the manufacturing area HF. This device is only due to the square sections outside of the component 10 enclosing installation space (not explicitly marked) indicated.

The heater 120 is preferably set up to form a temperature gradient below the manufacturing area. For this, the heater 120 for example and as in 1 marked four separately activatable and / or controllable heating modules ( 1M to 4M) include. Preferably, by means of the method described here and further below, directly below the production area HF for example a first heating module 1M set up to the highest by the heater 120 achievable temperature in the component 10 to reach.

A second heating module M2 is preferably set up and controllable to a gradually and / or slightly lower temperature in the component 10 to achieve or discontinue.

A third heating module M3 is preferably set up and controllable in order to maintain a lower temperature in the component 10 to achieve or discontinue.

A fourth heating module M4 is preferably set up and controllable in order to maintain a lower temperature in the component 10 to achieve or discontinue.

With increasing distance from the manufacturing area HF In the present case, a temperature that is gradually and / or monotonically falling in the component is preferred 10 reached.

The device can be used to limit or define the production area HF 100 for example a border 150 include which is above the heater 120 is arranged. The edge 150 can furthermore comprise or represent insulation for the thermal insulation of a space above the production area HF. Although this is not explicitly marked in the figures, for example, between the individual modules 1M to 4M thermal insulation must still be installed.

In order to be able to set and / or regulate the temperatures appropriately and efficiently along the intended temperature gradient, the device comprises 100 preferably further temperature sensors 140 , The temperature sensors 140 are preferably set up along a building direction z (compare vertical direction upwards). There is preferably at least one temperature sensor per heating module 140 provided so that about the measurement of the temperature and the heater 120 a customized temperature gradient in a simple manner via the heating device 120 can be set (see below).

The device further comprises 100 a lowerable construction platform 130 on which the component 10 preferably built up and "welded". During the additive construction of the component 10 becomes the build platform 130 preferably by a layer thickness (cf. S1 . S2 ) lowered the corresponding dimension so that the manufacturing area remains at the same z position.

The device 100 further comprises a first radiation device LS1 , in particular a first laser scanning system, for melting and then actually solidifying the base material P , By the first radiation device LS1 , for example using a laser or electron beam, the component 10 expediently selectively irradiated and remelted for its solidification. This is preferably done in part simultaneously with the application of new base material described above P , Likewise (at the same time) heat (after) treatment can be carried out by the heating device 120 , as indicated above, for already solidified parts of the component 10 (below the manufacturing area HF).

The device 100 further comprises a second radiation device LS2 , for example via a laser or electron beam, in particular a second laser scanning system, for preheating the base material P , The preheating can, for example, also be carried out simultaneously with the selective irradiation of the base material HF , preferably in another area of the manufacturing area HF , respectively.

Although this is not explicitly marked in the figures, the device can 100 similar to a device for crystal pulling using the so-called Bridgman-Stockbarger method, for example comprising a suitable crucible. Alternatively or additionally, the device 100 be set up via a suitable choice of the temperature gradient in the heating device 120 and, for example, a suitable coordination of preheating, radiation / remelting and heat treatment / heat aftertreatment a seed for the structure to be built S for the component 10 to build.

The method actually presented preferably comprises, as an additive manufacturing method, the selective irradiation of the base material P for the component 10 with a laser or electron beam B1 the first irradiation device LS1 ,

The radiation described is preferably carried out at least partially at the same time as the application of new base material P (cf. (i) in 3 ) for the construction of the component 10 , as described above and a heat treatment (cf. (ii) in 3 ) or post-heat treatment, for example by induction heating 120 immediately after the actual additive structure of the structure S for the component 10 ,

Selective irradiation (a), application (i) of powder P and heat treatment (ii), and optionally further process steps such as preheating (cf. (iii)), for example using a laser or electron beam B2 the second irradiation device LS2 (see below) or the gradual or gradual lowering of the construction platform 130 are preferably matched so that a structure S for the component 10 directionally frozen and / or epitaxially growing or being formed.

2 shows schematically a simplified top view of the manufacturing area HF which is circular according to the present embodiment. This configuration enables a simplified powder application through, for example, relative to the edge 150 rotatable application device 110 , A powder storage container is in for convenience 2 not marked. However, at least one powder outlet of the application device is shown 110 , in the form of a narrow slot which extends over the radial extent of the manufacturing surface HF extends from its center to the edge. The dashed lines are intended to indicate that this slot is for powder application P for example, also over the entire diametrical extent of the manufacturing surface HF or the construction platform 130 can extend.

In the way of the method described, remelting a) and the method steps of powder application (i) can be carried out by the application device 110 , the heat treatment (ii) and, optionally, the powder preheating (iii), in different areas of the production area HF, but are at least partially carried out simultaneously.

As in 2 It can expediently be recognized (clockwise) a preheating (iii), which is shown in simplified line form, of a powder application (i) by the application device 110 spatially follow, for example by 60 °. Likewise, an actual selective irradiation or remelting (compare method steps a) of previously applied base material can spatially follow the preheating described (iii), but at least partially take place simultaneously. The same applies to the heat treatment (ii), which is preferably carried out at least at the same time as the irradiation a).

It is in 2 to recognize that the left part of the manufacturing area HF already through the structure S is formed (compare hatching). An angular range from 0 to 120 °, ie areas in which powder is applied (i) and in which powder applied P is preferably only preheated to temperatures below the melting point, (iii), according to the exemplary embodiment of the 2 through powdery base material P educated.

The arrows in 2 , which are based on the reference numerals (i), (iii) and a), are intended to indicate the course of the process or the application of the corresponding process steps to the production area in a continuous manner and at least partially at the same time.

3 shows a schematic flow diagram, the simultaneous steps of selective irradiation, application, heat treatment and preheating likewise to be illustrated by the horizontally adjacent process steps a), (i), (ii) and (iii).

Method step b) is only intended to complete the component 10 suggest. This allows thermal or mechanical post-processing steps or simply removing the finished component from the device 100 be included.

The method presented advantageously allows components to be equipped with improved structural and / or crystallographic properties, in particular directionally solidified material phases and / or epitaxially and thus preferably at least partially single-crystalline properties. Epitaxial structure in the present case means that, for example, one layer S2 (at least in some areas) the crystal geographic orientation of a layer built up immediately beforehand S1 accepts. This results in decisive advantages with regard to the strength and susceptibility of the material to cracks or wear. The materials can preferably be constructed in an additive manner analogous to the Bridgeman process mentioned.

Accordingly, the component 10 after the build-up of individual welding beads or welding traces, which refer to the individual layers or sections produced (see reference numerals S1 . S2 in 1 ) indicate visible.

The invention is not limited to these by the description based on the exemplary embodiments, but encompasses every new feature and every combination of features. This includes in particular any combination of features in the patent claims, even if this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 2601006 B1 [0007]

Claims (11)

Additive manufacturing process for components (10) to be used in the hot gas path of turbomachines, comprising the selective irradiation (a)) of a base material (P) for the component (10) with a laser or electron beam (B1) simultaneously with: - (i) the application of new base material (P) for the construction of the component (10), and - (ii) a heat treatment, for example by induction heating (120), of an already irradiated material (S) for the component (10), the selective irradiation and the heat treatment being coordinated such that a structure (S) for the component ( 10) directionally frozen. Procedure according to Claim 1 , wherein a construction platform (130) on which the structure (S) for the component (10) is built is successively lowered during the selective irradiation and during the heat treatment. Procedure according to Claim 1 or 2 , wherein the application of new base material (P) by means of an application device (110) from above onto a manufacturing surface (HF) and by means of a rotational movement (α). Method according to one of the preceding claims, wherein a temperature gradient is formed as part of the heat treatment below a manufacturing area (HF). Procedure according to Claim 4 , a higher temperature is set near the production area (HF) and - with increasing distance from it - a, for example gradually and / or monotonically falling temperature. Method according to one of the preceding claims, wherein the structure (S) for the component (10) is constructed epitaxially. Method according to one of the preceding claims, wherein base material (P) is preheated (iii) before the selective irradiation with a laser or electron beam (B2). Component (10) producible or manufactured by the method according to one of the preceding claims, further comprising a directionally solidified and / or single-crystal structure (S) with welding traces, which show at least largely epitaxial crystal growth of individual layers (S1, S2). Device (100) for the additive manufacturing of a component (10) according to the method according to one of the Claims 1 to 7 , comprising: - an application device (110) for applying base material (P) to a production area (HF), - an inductive heating device (120) for zone melting or forming a temperature gradient below the production area (HF) and - a lowerable construction platform (130 ), the device (100) furthermore having temperature sensors (140) along a direction of construction (z), and wherein the building platform (130) and the application device (110) are furthermore movable, in particular rotatable, relative to one another. Device (100) according to Claim 9 which has a first radiation device (LS1), in particular a first laser scanning system, for melting the base material and a second radiation device (LS2), in particular a second laser scanning system, for preheating the base material (P). Device (100) according to Claim 9 or 10 , wherein the construction platform (130) is set up to form a seed for the structure (S).

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