EP3658315A1

EP3658315A1 - Method for irradiating a powder layer in additive production using continuously defined production parameters

Info

Publication number: EP3658315A1
Application number: EP18779271.8A
Authority: EP
Inventors: Ole Geisen
Original assignee: Siemens AG
Current assignee: Siemens Energy Global GmbH and Co KG
Priority date: 2017-10-02
Filing date: 2018-09-18
Publication date: 2020-06-03
Also published as: US11846928B2; CN111163883B; WO2019068455A1; US20200353679A1; EP3461571A1; CN111163883A

Abstract

The invention relates to a method for providing data for selectively irradiating a powder layer in additive production, the method comprising: providing a predefined component geometry for a component (10); dividing the component geometry (10) into at least one first component layer (S1) and an overlying second component layer (S2) for additive production, wherein a contour (B) of the second component layer (S2) is incongruent with a contour (A) of the first component layer (S1); and continuously defining at least one production parameter (HP) for additively producing the second component layer (S2) in region (X) of a molten bath of a contour (A) of the first component layer (S1). The invention also relates to a corresponding component and computer programme product.

Description

description

Process for irradiating a powder layer in additive production with continuously defined production parameters

The present invention relates to a method for or as part of an additive manufacturing process. The method relates in particular to the provision of data or information for the selective irradiation of a powder layer in additive production.

The present invention further relates to a corresponding additive manufacturing method and to a component produced according to this method. Furthermore, the ahead ^¬ invention relates to a computer program or computer program product and a corresponding computer-readable medium.

Generative or additive processes for the production of components include, for example as powder bed processes, selective laser melting (SLM) or laser sintering (SLS), or electron beam melting (EBM).

Laser deposition welding (LMD) is also one of the additive processes.

A method for selective laser melting is known, for example, from EP 2 601 006 B1. Additive manufacturing processes ("additive manufacturing") have proven to be particularly advantageous for complex or complicated or filigree-designed components, for example labyrinth-like structures, cooling structures and / or lightweight structures Chain of process steps advantageous because a manufacturing or manufacturing step ei ^¬ nes component can be done directly on the basis of a corresponding CAD file. Furthermore, additive manufacturing has hitherto been particularly advantageous for the development or production of prototypes which can not or can not be produced efficiently by means of conventional subtractive or machining processes or casting technology.

The component as described herein is preferred ^¬ for use in a turbomachine, vorzugswei ^¬ se provided in the hot gas path of a gas turbine. The component preferably consists of a nickel-base or superalloy, in particular a nickel- or cobalt-based superalloy, or comprises such an alloy. The alloy can furthermore preferably be precipitation-hardened, oxidation-hardened and / or dispersion-hardened.

The additive production requires the selective irradiation of a powder layer with preferably predefined irradiation or production parameters. The corresponding parameters must be selected at least partially depending on the geometry of the component. Depending on whether a Randbe ^¬ rich or a contour of the component or for the component ak ^{¬ is} currently irradiated or an internal area, the parameters with respect to an optimal material structure - such as surface quality, hot crack susceptibility - to vary the component. This is particularly the case, since heat input into or heat dissipation from a molten bath during additive production is dependent on the current (lateral) position or region or layer to be solidified.

In addition, in particular, those production ^parameters which are to be selected for the production or irradiation of a contour of the component must be specifically adapted to whether the new or currently to be solidified component layer is supported by an underlying (constructed or manufactured) structure or, for example projects laterally beyond this or overhangs. Despite some "design freedom", for example, of selective melting drive, is the additive producing overhanging structures of the described components known to be a major challenge. Overhanging regions of the component, in particular ^¬ sondere those having an approach angle of more than 45 °, for example, extremely difficult or impossible by means of SLM or EBM manufacture.

In particular, the component contour of a built-up and / or layer to be consolidated for the component often includes so-called "downskin areas" or overhangs, together with "upskin" areas, which are supported by an underlying layer. A component contour in a upSkin area preferably has vertical walls or Kon ^¬ structures which extend, for example, parallel to the assembly direction of the component.

Depending on which contour the component should have in accordance with its geometry straight, unterschiedli ^¬ che manufacturing or irradiation parameters are assigned accordingly.

In the present case, the parameters mentioned characterize preferably so-called vectors for the irradiation of the component, or an irradiation or exposure trajectory or a corresponding path, according to which an energy beam, for example a laser beam, is passed over the powder bed in order to selectively and correspondingly provide corresponding starting powder to solidify the desired geometry of the component. The energy beam can be meandered over the powder bed to remelt and solidify the largest possible area. Individual irradiation paths, which may belong to the vector, are preferably only slightly separated from each other, so that a molten bath reaches the entire surface of the powder bed to be melted, and possibly so that an adjacent, already solidified web or track is at least partially remelted. Irradiations contour at the edge of the respective layer are ^¬ additionally to the irradiation of a component layer in the inside, as described above, it is necessary or advantageous. Usually, the different vectors (for example "downskin" or "upskin" are provided with their own parameters.) This leads to unfavorable interrupted, unsteady or discontinuous contour irradiation and thus to inefficiently long process or assembly times and in addition to instabilities in the molten bath during powder consolidation For example, at each interruption or change in the irradiation path, a repeated "ignition", "Anfah ^¬ Ren" and / or adjusting the required for the solidification irradiation device is necessary.

It is therefore an object of the present invention to provide agents which solve the difficulties or problems described, in particular significantly improve the structural quality of additively produced components.

This object is achieved by the subject matter of the independent Pa ^¬ tentansprüche. Advantageous embodiments are subject of the dependent claims ^¬ Ge.

One aspect of the present invention relates to a method for providing data or information for the selective irradiation of a powder layer in additive manufacturing, comprising providing a predefined component geometry, for example in the form of a CAD file, for the component.

The method further includes dividing the component geometry into at least a first device layer and an overlying second component layer for additive Her ^¬ position, wherein a contour of the second component layer is de ^¬ ckungsverschieden or incongruent of a contour of the first component layer. In other words, there is at least one upskin or downskin area.

The method further comprises continuously or ste ^¬ term defining at least one production parameter for an additive manufacturing of the second component layer in the loading rich of a molten bath or a heat-affected zone, for example, a contour of the first (underlying) component layer. In other words, the parameter is preferably defined continuously or continuously in those areas where the contours (the first and second component ^{layers ¬} ) intersect over the width of the molten bath.

Said method is preferably a computer-implemented method. That is to say, that at least some process steps described in this connection are partially or completely carried out by means of general Datenverar ^¬ processing. Preferably, the process steps of dividing the component geometry and the continuous defining the at least one herstel ^¬ lung parameters (as described) are partially or completely carried out by means of data processing. The Ready ^¬ make the component geometry can, for example, by other than belonging to the data processing means SUC ^¬ gen, manual, for example, by fully or partially benut ^¬ zergesteuertes loading a CAD file or other Informati ^¬ tions or data or by entering.

The term "computer-implemented method" can not be understood in particular ^¬ sondere so that all process must be completed by general means of Datenverar ^¬ processing steps.

The described invention, in particular said method, a higher Prozessproduk- is advantageously faster tivity by exposing the contour without interrup ^¬ deviations possible. Further allows the described Ver ^¬ drive the construction of components having a lower Fehlstellen- centers or crack density. Since the edges of the molten bath in the additive preparation with regard to their solidification or reaction kinetics are typically unstable, the continuous definition of the parameter allows a decisive improvement ^¬ Dende or favoring the Schmelzbadkinetik by smooth transitions in the contour irradiation and sämt- lent manufacturing parameters. Thus, the risk of cracking and / or defect formation in additive manufacturing is significantly reduced. This means, in particular in the additive production of high-temperature-loaded components, for example gas turbines, groundbreaking advantages.

Furthermore, with the described means, the surface quality of the components, including comprehensive internal Oberflä ^¬ Chen, significantly improved.

In other words, there is a potential to make additive manufacturing reproducible and / or even applicable to mass production of high temperature loaded components.

A further aspect of the present invention relates to a method for producing the component from a powder bed comprising the selective irradiation according to the method described above, wherein the component is irradiated with an energy beam, preferably a laser or electron beam, according to the continuously defined production parameters / or produced additive.

A further aspect of the present invention relates to a component which can be produced or manufactured according to the described production method, comprising a lower density of defects, crack centers and / or a lower probability of forming compared to a conventional component (the prior art) Missing or hot cracks. As a result, the component can advantageously be reproduced and improved

Structure and dimensional stability are produced.

A further aspect of the present invention relates to a computer program or computer program ^product comprising ^instructions which, during the execution of the program by a data processing ^device (computer), cause it to Process for providing data for the selective irradiation.

Another aspect of the present invention relates to a computer program product comprising emerge the data for the selekti ^¬ ve irradiation of the powder layer, which are provided by the method for providing the corresponding data or information for the selective irradiation or out of the described computer program.

Another aspect of the present invention relates to a computer-readable medium or storage medium comprising instructions that, when executed by a computing device, cause it to perform the method of providing data for selective irradiation. The computer program described can be stored on the computer-readable medium.

In one embodiment, the production parameter designates or comprises a geometry of a contour irradiation pattern for the additive production of the component. For example, by selective laser melting - - according to this design from ^¬ the molten bath, which in the selective irradiation of the powder bed to solidify an output ^¬ materials can be generated advantageously conducted stably and continuously over the powder bed. As an advantage, it does not abruptly break the molten bath, which can prevent the described instabilities. In one embodiment referred to or herstel ^¬ development parameter includes a contour manufacturing parameters.

In one embodiment referred to or production of parameters comprises at least one radiation parameter or a beam property of the additive producing the construction ^¬ part, for example a parameter selected from: Strah ^¬ lung intensity, energy density, radiation power, Strah ^¬ lung power density, polarization, pulsing and irradiation because length. The irradiation wavelength may be a laser wavelength or, in the case of a particle beam, a de Broglie wavelength. According to this Substituted ^¬ staltung, in addition to the described advantages of the preceding embodiment of the entire additive Aufbaupro- process based on the irradiation parameters continuously, that is for example, without discontinuities in or discontinuities, are performed. In one embodiment referred to or herstel ^¬ development parameter includes a contour of the irradiation parameters.

In an embodiment, the continuous defining comprises a plurality of manufacturing parameters comprising at least one parameter selected from: heat input, melt pool width, beam offset, irradiation speed, size of a

Beam cross section on the powder bed, irradiation angle, flow rate or flow rate of a protective gas flow, conditions of the protective gas flow regulating gas valves, ambient pressure and alloy composition of a powder. According to this embodiment particularly advantageous sämtli ^¬ che can be continuously defined to be selected or selectable parameters or adapted for the additive construction of the component. The number of parameters can easily exceed 100.

In one embodiment, the second component layer has an area that overhangs or protrudes beyond the first component layer. In one embodiment, the overhanging region, for example, from a standard production parameter set (for example, 90 ° contours or 90 ° walls) deviating overhang production parameters are assigned. In one embodiment, the second component layer has a supported region which lies within the contour of the first component layer and, for example, from this

is spaced. In one embodiment, the supported region is assigned, for example, support production parameters deviating from the standard production parameter set.

In one embodiment, the component geometry is subdivided into a plurality of component layers arranged one above the other, for example, in a number between 1000 and 10000 component layers.

In one embodiment, production parameters of at least some of these component layers in the region of a molten bath or a heat-affected zone of a contour of a respectively underlying component layer are continuously defined.

In one embodiment, the method is or comprises a CAM method for preparing the additive production of the component.

Embodiments, features and / or advantages that relate herein to the method for providing data for the selective irradiation, the additive manufacturing process, the component which Computerpro ^¬ program [product] or the computer readable medium may further relate to and vice versa.

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

FIG. 1 shows a schematic sectional view of a part of a component during its additive production.

FIG. 2 shows a schematic plan view of at least one

Part of a component, on the basis of the selective Be ^¬ radiation for the additive production of the component is indicated. FIG. 3 shows a detailed view of a region of the plan view from FIG. 2.

FIG. 4 shows a schematic plan view analogous to FIG. 2, by means of which method ^steps according to the invention are interpreted.

FIG. 5 shows a schematic flow diagram, which according to the invention indicates method steps. In the exemplary embodiments and figures, identical or similar elements in each case with the same Bezugszei ^¬ surfaces may be provided. The illustrated elements and their proportions with each other are basically not to be regarded as true to scale, but individual elements, for better representation and / or better understanding exaggerated be shown thick or large.

FIG. 1 shows a schematic sectional view or side view of at least one part of an additive component 10 to be produced. The component 10 is preferably indicated during its additive, generative or layered production, with a first layer S1 and one arranged along the construction direction AR above the first layer second layer S2 was already selectively irradiated by an irradiation device (not explicitly indicated) and thus solidified and produced.

The solidification, for example by a laser or

Electron beam (compare SLM and EBM method) is preferably carried out by selective solidification of a base material of a powder bed 2. The first layer Sl is thereby materially connected to an underlying substrate or ei ^¬ ner construction platform 1 or welded. This is done by rasterizing the starting material or the powder bed 2, for example in rows or meanders, with the energy beam, for example a laser beam. It is with the beam a molten bath over the surface of the Led powder bed, which immediately solidifies after passing the La ^¬ sers to a newly constructed component layer.

The finished component 10 preferably comprises the layers S1, S2 and all other layers to be built thereon, up to the layer SN (indicated by dashed lines).

The component is preferably a hot gas path of a Gastur ^¬ bine-applied, high-temperature-stable component. Demgeß are already made special demands on the powder ^¬ bed 2 forming starting material. The starting materials ^¬ rial preferably refers to a precipitation-hardened, and especially high-temperature and - due to its crack-prone ^¬ ness difficult to weld - superalloy, such as egg ner nickel-based alloy. The low-defect possible Aufschmel ^¬ zen / welding, which is required for the additive built, already provides for simple geometries because of participating in the additive building process high temperature gradients and complicated reaction kinetics foal of a particular challenge and one of the key constraints in the establishment of additively manufactured withstand high temperatures Components represent.

Another difficulty arises when additionally complex component geometries are to be realized in additive manufacturing.

The layer S1 has preferably been coated in the context of an SLM or EBM process with a further layer of powder or starting material, which was then irradiated according to the geometry of the component and solidified in the form of the layer S2.

The geometry of the component 10 requires in this case that the layer S2 (not labeled ex ^¬ plicitly) protrudes laterally at the edge of the component 10 over the layer Sl in an overhanging portion or overhang portion UB. Since an angle of less than 45 ° (see Fig. 1) of an overhanging area in the additive production of the components described are not or only extremely difficult to implement, the overhanging area UB is, for example, in comparison to a supported or supporting area SB, in which the layer S2 is completely ge ^¬ supported by the layer Sl, small or narrow. For example, the overhanging area UB at the right edge of the component 10 in FIG. 1 is accordingly to be built up or irradiated with different production parameters or irradiation parameters than the left edge of the component which is completely supported by the layer S1.

Figure 2 indicates in plan view that described in Figure 1 component or a single component layer to a ^¬ irradiation pattern or contour irradiation vectors for the construction of the component additive 10th

The line A indicates a contour of the first layer Sl.

On the other hand, the dashed line B indicates a contour of the second layer S2 lying above the first layer. The second layer S2 is thus different from the first layer Sl or incongruent to this. In the plan view of Figure 2 however, there are areas which overlap, so ^¬ that the layer 2, as indicated by the outline B, supported and overhanging areas describes. In other words, the contour B defined relative to the contour A, the geometry ^¬ change of the component 10 along an assembly direction AR (in Figure 2 viewed from the paper plane).

At a constant distance to the line A is connected to the like shape of the contour areas A a X of the molten bath during the additive preparation or a heat affected zone which must not necessarily be completely melted, indicated ^¬. In the region X of the molten bath or the contour line B shown interrupted, which is to indicate that in the ^¬ X sem range conventionally interruptions or Discontinuities in any manufacturing parameters. This has a negative effect on the structure of the component 10. In the supported area SB described above, the line B is shown dotted, which is intended to imply that in this area the layer S2 is completely carried by the layer Sl. In contrast, the contour B in an overhanging region UB (the layer S2 relative to the layer Sl) dashed ge ^¬ indicates.

Production parameters, for example irradiation parameters are, by default, and depending on whether an overhang contour (see FIG. UB), a standard contour or standard wall or a fully-supported Be ^¬ rich (see FIG. SB) to be irradiated (not explicitly identified), selected to be different.

The said production parameter may additionally include as irradiation parameters, for example, a radiation intensity, energy density, radiation power, radiation power density, polarization, pulsation or an irradiation wavelength. Accordingly, an amount of one of the described parameters in the overhanging region may, for example, be chosen to be greater or less than the amount of the same parameter in the supported region to achieve optimum structural or surface quality of the component 10. The optimum adjustment thereof or other parameters is very sensitive, since, for example, a too large or too small selected radiation power can locally already lead to a greatly increased density of defects, porosities or crack centers or "crack germs".

As an alternative or in addition to the variables described, a production parameter may contain specific parameters of an additive manufacturing plant (not explicitly indicated) in FIG general, for example, heat input, Schmelzbadbreite, beam offset, irradiation speed, size of a beam cross section on the powder bed, Irradationwin ^¬ angle, flow rate or flow velocity of a protective gas flow, conditions of the protective gas flow regulating gas valves, ambient pressure or even an alloy composition of the powder. The number of parameters is necessary can be described adequately by an additive manufacturing process umfas ^¬ transmitted or reproduced easily exceed the number of 100, as will be apparent from the examples described above. Each of these quantities can be understood here as a production parameter.

The solid areas or portions of contour B, i. in the regions X, which intersect or intersect the molten bath of the underlying layer Sl or its edge contour, consequently describe an abrupt step in the irradiation pattern and thus also in all production parameters.

FIG. 3 shows a detail view of the plan view from FIG. 2 (upper left corner). It can be seen that in the region of the molten bath or zone, which in this case has a width Δ of 500 ym or less, for example 200 ym, a jump occurs both in the contour B (shown in solid line in FIG. 2) and consequently, of course also occurs in the corresponding irradiation and Herstellungspa ^¬ parameters. This jump leads to unfavorable structural results of the

Component 10, in particular the layer S2, since neither the contour nor the over the range X to be elected manufacturing or coating parameters are continuously defined. The jump and the said discontinuity in the Konturbe ^¬ radiation or the speaking production parameters occurs as in Figure 3 indicated preferably in the range X of the layer Sl, so that the area on which the layer S2 separates the overhanging area UB from the supporting area SB.

FIG. 4 shows a situation comparable to that of FIG. 2, whereas, however, method steps according to the invention have been used in order to prevent the described discontinuity and the associated disadvantages. In FIG. 4, again, the contour A is drawn with the region X surrounding it (slightly rotated to the right in comparison to FIG. 2). The contour B is also shown in dashed lines in at least a similar manner as in FIG. In the overhanging region UB and the supporting or supported region SB, the irradiation together with the corresponding production parameters preferably behaves as in FIG. 2 or known in the prior art. In the regions X, in which - as can be seen from FIG. 3 - usually a jump in the contour irradiation occurs, and thus also a discontinuity in the amounts of the production parameters, a continuous transition in the contour B is now shown. According to the method according to the invention, a specific irradiation vector (contour irradiation) is now defined in the region of the molten bath of the contour of an underlying layer (compare layer S1). In addition, all manufacturing parameters described above, the component 10 may be due to the presence in this area continuously defined irradiation vectors not only irradiation vectors, such as the radiation Leis ^¬ tung-tight, radiation wavelength or laser power, son ^¬ countries, for example, gradually and steadily defined or adjusted, according to which, Finally, it is also built to use the advantages of the invention. The (gradual) adjustment takes place preferably (but not not ^¬ sarily) directly to the those parameters accordingly be established over layer (see layer S2), which are selected in the overhanging portion UB and the supporting region SB. This, in contrast to jumps or discontinuities in the contour irradiation and the corresponding production parameters for the additive process, has decisive advantages, such as a higher productivity through faster exposure of the contour without interruptions, fewer defects or crack centers, since a "beginning" and "end" of the molten bath (compare the area X) can not be performed but unstable kon ^¬ continuously and stably. episode are white ^¬ terhin an improved structure, surface quality and improved dimensional stability for the component 10.

As indicated with reference to Figure 1 of the invention ^shown SSE method for additive manufacturing of the component 10 comprises the division of a corresponding part geometry into a plurality of superposed layers component Sl, S2 to SN. This can correspond to a number between 1000 and 10000 component layers, production ^parameters HP of at least some of these component layers in the region X of the molten bath of a contour of a respective underlying component layer S1 being continuously defined as described.

The finished component 10 preferably comprises a lower density of imperfections, crack centers and / or a lower probability of forming defects or hot cracks in comparison to a component of the prior art or a conventionally produced component. Figure 5 indicates reference to a schematic flowchart Ver ^¬ method steps of the inventive method:

The method is preferably a method for providing Stel ^¬ len data for the selective irradiation of a powder layer in the additive manufacturing. In this sense, the inventive method preferably describes a part of an additive manufacturing process itself. This comprises drive ^¬ Ver, a), providing a predefined Component geometry for the component 10 (see layers Sl, S2 to SN in Figure 1). The component geometry is preferably ^{¬ given} by a CAD file or corresponding design ^¬ data. Alternatively, the component geometry may be digitized by a measurement of an already exist ^¬ the component 10 are provided.

The method further comprises, b), further subdividing the component geometry 10 into at least one first component layer S1 and an overlying second component layer S2 for the additive manufacturing, wherein a contour B of the second component layer S2 is congruent to a contour A of the first component layer S1 ( see above) . The subdivision including the following method steps is preferably to be regarded as part of a CAM method for preparing the ad ^¬ ditive production of the component 10.

The method further comprises, c) the continuous De ^¬ finishing at least one production parameter HP for an additive manufacturing the second component layer S2 in the range X of a molten bath of the contour A of the first device layer Sl as described above.

Accordingly, in principle, all described process steps are carried out, optionally, up to the physical actual structure of the component itself, by means for Datenverarbei ^¬ tung, for example, a data processing device or a computer. The invention is not limited by the description based on the embodiments of these, but includes each new feature and any 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 stated in the patent claims or exemplary embodiments.

Claims

claims

A computer-implemented method for providing data for the selective irradiation of a powder layer in additive manufacturing, comprising the following steps:

a) providing a predefined component geometry for a component (10),

b) subdividing the component geometry (10) into at least one first component layer (S1) and an overlying second component layer (S2) for additive production, wherein a contour (B) of the second component layer (S2) ^overlaps the contour ( A) is the first component layer (Sl),

- c) continuously defining at least one herstel ^¬ lung parameters (HP) (for an additive manufacturing the two-th component layer S2) in the region (X) of a molten bath ei ^¬ ner contour (A) of the first component layer (Sl), the production parameters ( HP) designates a geometry of a contour radiation pattern for the additive production of the component (10).

2. The method of claim 1, wherein the Herstellungsparame ^¬ ter (HP) refers to at least one irradiation parameters for the additive producing the component selected, for example, egg ^¬ NEN parameters: radiation intensity Energiedich- te, radiation power, radiation power density Bestrah ^¬ lung wavelength.

3. The method according to claim 1, comprising continuously defining a plurality of production parameters (HP) comprising at least one parameter selected from: heat input, melt pool width, beam offset, irradiation speed, size of a beam cross section on the powder bed, irradiation angle, flow rate or flow rate ,

Flow velocity of inert gas flow, conditions of inert gas flow regulating gas valves, ambient pressure, alloy composition of a powder.

4. The method according to any one of the preceding claims, wherein the second component layer (S2) has a over the first component ^¬ layer overhanging region (UB).

5. The method according to claim 4, wherein the overhanging area (UB), for example, deviating from a standard manufacturing parameter set, overhang production parameters (UB) are assigned.

6. The method according to any one of the preceding claims, wherein the second component layer (S2) has a supported region (SB), which is within the contour (A) of the first component layer (Sl) and spaced therefrom.

The method of claim 6, wherein the supported area

(SB), for example, different from a standard manufacturing parameter set, support production parameters (SP) are assigned.

8. The method according to any one of the preceding claims, wherein the component geometry is divided into a plurality of superimposed ^¬ associated component layers (Sl, S2, SN), for example in a number of between 1000 and 10,000 component layers ^¬, and wherein production parameters (HP) of at least some of these component layers in the region (X) of a molten bath of a contour of a respectively underlying component layer (Sl) are defined continuously.

9. The method according to one of the preceding claims, which is a CAM method for preparing the additive production of the component (10).

10. A method for additive manufacturing of a component (10) from a powder bed (2) comprising the selective irradiation according to the method according to any one of the preceding claims, wherein the component (10) according to the continuously defined manufacturing parameters (HP) irradiated with an energy beam and is produced additive.

11. A component which can be manufactured or manufactured according to the method of claim 10, comprising, in comparison to a component of the prior art, a lower density of defects, crack centers and / or a lower probability of the formation of defects or hot cracks.

12. A computer program product comprising the data for the se ^¬-selective irradiation of the powder layer which is provided by the Ver ^¬ drive according to one of claims 1 to 10 or ^¬ to emerge from the computer program according to claim 12th

13. A computer-readable medium comprising instructions which, when executed by a data processing device, cause them to perform the method according to one of claims 1 to 10.