METHOD FOR PRODUCING A COMPONENT BY MEANS OF AN ADDITIVE MANUFACTURING METHOD USING A LASER

Abstract

A method for producing a component by means of an additive manufacturing method using a laser is proposed, the method comprising the following steps: (a) providing a metal powder, (b) applying a powder layer (18) of the metal powder to a build platform (14) of a process chamber (12), (c) introducing a first process gas into the process chamber (12), (d) melting a first selected region (36) of the applied powder layer (18) by means of a laser in a first atmosphere which includes the first process gas, (e) introducing a second process gas into the process chamber (12), wherein the second process gas differs from the first process gas at least in terms of its composition and/or its pressure, and (f) melting a second selected region (38) of the applied powder layer (18) by means of the laser in a second atmosphere which includes the second process gas, wherein the second selected region (38) differs from the first selected region (36).

Claims

1. Method for producing a component by means of an additive manufacturing method using a laser, the method comprising the following steps: (a) providing a metal powder, (b) applying a powder layer of the metal powder to a build platform of a process chamber, (c) introducing a first process gas into the process chamber, (d) melting a first selected region of the applied powder layer by means of a laser in a first atmosphere which includes the first process gas, (e) introducing a second process gas into the process chamber, wherein the second process gas differs from the first process gas at least in terms of its composition and/or its pressure, and (f) melting a second selected region of the applied powder layer by means of the laser in a second atmosphere which includes the second process gas, wherein the second selected region differs from the first selected region.

2. Method according to claim 1, furthermore comprising repeating, in particular repeating multiple times, at least steps (a) to (d) and/or repeating, in particular repeating multiple times, steps (e) and (f).

3. Method according to claim 1, wherein the metal powder is a metal alloy, in particular aluminium alloy, or the metal powder is composed of at least 55% Fe, in particular at least 75% Fe and at most 99% Fe, in particular at most 80% Fe, preferably at least 1% Ni, in particular at least 10% Ni and at most 24% Ni, preferably at least 1% Cr, in particular at least 8% Cr and at most 35% Cr, and also at least one additional alloying element selected from the group consisting of C, Mo, Mn, Cu, W, V, Si, Ta, Nb and Ti.

4. Method according to claim 1, wherein the first process gas and/or the second process gas include(s) at least one gas selected from the group consisting of: argon, helium, nitrogen, carbon monoxide, carbon dioxide, methane, propane, hydrogen and oxygen.

5. Method according to claim 1, wherein the first process gas and the second process gas include hydrogen, wherein the concentration of hydrogen in the first process gas is higher than the concentration of hydrogen in the second process gas.

6. Method according to claim 1, wherein during the melting in step (d) and/or in step (f) a pressure in the process chamber is varied.

7. Method according to claim 1, furthermore comprising at least partially heat treating the applied layer during the melting in step (d) and/or in step (f) and/or at least partially heat treating the applied layer after the melting in step (d) and/or in step (f), wherein the heat treatment comprises melting, sintering, annealing, stress relief annealing, diffusion annealing or low hydrogen annealing, with the heat treatment preferably being effected by means of a defocused laser.

8. Method according to claim 1, furthermore comprising arranging a glass plate at a predetermined distance from the applied powder layer, the predetermined distance being in a range from 0.5 mm to 20.0 cm and preferably from 1.0 cm to 10.0 cm, wherein the first process gas and/or the second process gas are introduced into the process chamber in such a way that a laminar gas flow above the applied powder layer is generated.

9. Method according to claim 1, wherein the laser oscillates during the melting in step (d) and/or in step (f), and/or a power and/or a focus of the laser are varied during the melting in step (d) and/or in step (f).

10. Method according to claim 1, wherein the melting in step (d) is carried out in such a way that the first selected region is at least partially melted again, and/or the melting in step (f) is carried out in such a way that the second selected region is at least partially melted again.

11. Method according to claim 1, furthermore comprising applying or introducing at least one alloying element, especially in the form of a suspension, onto/into the applied powder layer in the first selected region and/or in the second selected region.

12. Method according to claim 11, wherein the alloying element is applied or introduced by means of a printhead.

13. Method according to claim 1, wherein the melting in step (d) is carried out in such a way that the first selected region after a subsequent cooling has a first metallurgical structure, wherein the melting in step (f) is carried out in such a way that the second selected region after a subsequent cooling has a second metallurgical structure, and wherein the second metallurgical structure differs from the first metallurgical structure.

14. Method according to claim 1, furthermore comprising changing between the first process gas and the second process gas by moving a sealing slide (56) within the process chamber relative and in particular parallel to the build platform.

15. Apparatus for producing a component by means of an additive manufacturing method using a laser, comprising: a process chamber having a build platform, an application apparatus, in particular a doctor blade, for applying a powder layer of a metal powder to the build platform, a process gas nozzle for introducing process gas into the process chamber, at least one laser source for emitting a laser onto the powder layer and a valve assembly for the selective supply of process gas to the process gas nozzle, wherein the valve assembly has at least a first valve path and a second valve path, wherein the valve assembly is connectible to a first process gas source and to a second process gas source, wherein the first valve path and the second valve path are actuable separately from one another in such a way that a first process gas from the first process gas source and/or a second process gas from the second process gas source are selectively introducible into the process chamber by means of the process gas nozzle.

16. Apparatus according to claim 15, furthermore comprising a control apparatus for automatically controlling the valve assembly on the basis of numerical data which define the geometric form of the component to be produced.

17. Apparatus according to claim 15, furthermore comprising a sealing slide, wherein the sealing slide is movable within the process chamber relative and preferably parallel to the build platform.

18. Apparatus according to claim 17, wherein the sealing slide is connected to the application apparatus, wherein the application apparatus is movable relative to the build platform.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0169] Further optional details and features of the invention are apparent from the following description of preferred examples shown diagrammatically in the figures.

[0170] In the figures:

[0171] FIGS. 1A to 1D show an apparatus for producing a component by means of an additive manufacturing method using a laser in various steps of a method for producing the component,

[0172] FIG. 2 shows a Schaeffler diagram for chromium-nickel steels,

[0173] FIGS. 3A and 3B each show an enlarged section of a component having different microstructures,

[0174] FIG. 4 shows a further apparatus for producing a component by means of an additive manufacturing method using a laser,

[0175] FIG. 5 shows a side view of a further apparatus for producing a component by means of an additive manufacturing method using a laser,

[0176] FIG. 6 shows a top view of the apparatus of FIG. 5, and

[0177] FIGS. 7A to 7C show top views of a further apparatus for producing a component by means of an additive manufacturing method using a laser in various operating states.

EMBODIMENTS OF THE INVENTION

[0178] FIGS. 1A to 1D show an apparatus 10 for producing a component by means of an additive manufacturing method using a laser in various steps of a method for producing the component. The apparatus 10 has a process chamber 12 having a build platform 14, an application apparatus 16 for applying a powder layer 18 of a metal powder to the build platform 14, a process gas nozzle 20 for introducing process gas into the process chamber 12, at least one laser source 22 for emitting a laser onto the powder layer 18 and a valve assembly 24 for the selective supply of process gas to the process gas nozzle 20. The valve assembly 24 has at least a first valve path 26 and a second valve path 28. The valve assembly 24 is connectible to a first process gas source 30 and to a second process gas source 32. The first valve path 26 and the second valve path 28 are actuable separately from one another in such a way that a first process gas from the first process gas source 30 and/or a second process gas from the second process gas source 32 are selectively introducible into the process chamber by means of the process gas nozzle 20. The application apparatus 16 in the embodiment shown is a doctor blade. The apparatus 10 furthermore has a control apparatus 34. The control apparatus 34 is designed for automatically controlling the valve assembly 24. The actuation is effected in this case on the basis of numerical data which define the geometric form of the component to be produced. Accordingly, the control apparatus 34 enables a supply of the first process gas from the first process gas source 30 into the process chamber 12 via the first valve path 26, a supply of the second process gas from the second process gas source 32 into the process chamber 12 via the second valve path 28, or a supply of a mixture of the first process gas and the second process gas. It is explicitly emphasized that the valve assembly 24 may have further valve paths and can be connected to further process gas sources so that mixtures of three or more process gases are also suppliable into the process chamber 12. The first process gas and/or the second process gas include(s) at least one gas selected from the group consisting of: argon, helium, nitrogen, carbon monoxide, carbon dioxide, methane, propane, hydrogen and oxygen. For example, the first process gas and the second process gas include hydrogen, wherein the concentration of hydrogen in the first process gas is higher than the concentration of hydrogen in the second process gas.

[0179] In the embodiment shown, the control apparatus 34 is furthermore designed to control the laser source 22, the build platform 14 and the application apparatus 16.

[0180] The method for producing a component by means of an additive manufacturing method using a laser is described in detail hereafter on the basis of FIGS. 1A to 1D. First, the metal powder is provided. The metal powder can for example be provided in a powder store (not illustrated in more detail) of the apparatus 10. The metal powder is preferably a metal alloy. The metal powder can for example be composed of at least 55% Fe, in particular at least 75% Fe and at most 99% Fe, in particular at most 80% Fe, preferably at least 1% Ni, in particular at least 10% Ni and at most 24% Ni, preferably at least 1% Cr, in particular at least 8% Cr and at most 35% Cr, and also at least one additional alloying element selected from the group consisting of C, Mo, Mn, Cu, W, V, Si, Ta, Nb and Ti. Alternatively, the metal powder may be an aluminium alloy. A powder layer 18 of the metal powder is applied to the build platform 14 by means of the application apparatus 16. As shown in FIG. 1A, the first process gas is introduced into the process chamber 12. In particular, the process chamber 12 is flooded with the first process gas. For this purpose, the control apparatus 34 actuates the valve assembly 24 in such a way that the first valve path 26 is opened and the first process gas can flow out of the first process gas source 30 and into the process chamber 12.

[0181] As shown in FIG. 1B, a first selected region 36 of the applied powder layer 18 is subsequently melted by means of a laser, emitted by the laser source 22 onto the first selected region 36, in a first atmosphere which includes the first process gas. The first selected region is situated in the centre of the powder layer 18 merely by way of example. In this case, the control apparatus 34 controls the laser source 22 with respect to the position of the laser, the power of the laser, etc., on the basis of the geometric data for the component to be produced and of the desired microstructure in the first selected region 36. The melting is effected in particular in such a way that the first selected region 36 during subsequent cooling becomes permanently bonded. Since the powder layer 18 is arranged directly on the build platform 14, this permanent bond is formed with the build platform 14. The melting can be carried out in such a way that the first selected region after a subsequent cooling has a first metallurgical structure.

[0182] As shown in FIG. 1C, the second process gas is subsequently introduced into the process chamber 12. In particular, the process chamber 12 is flooded with the second process gas. For this purpose, the control apparatus 34 actuates the valve assembly 24 in such a way that the second valve path 28 is opened and the second process gas can flow out of the second process gas source 32 and into the process chamber 12. The second process gas differs from the first process gas at least in terms of its composition and/or its pressure.

[0183] As shown in FIG. 1D, a second selected region 38 of the applied powder layer 18 is subsequently melted by means of a laser, emitted by the laser source 22 onto the second selected region 38, in a second atmosphere which includes the second process gas. The second selected region 38 differs from the first selected region 36. For example, the second selected region 38 surrounds the first selected region 36. Here, the control apparatus 34 controls the laser source 22 with respect to the position of the laser, the power of the laser, etc., on the basis of the geometric data for the component to be produced and of the desired microstructure in the second selected region 38. The melting is effected in particular in such a way that the second selected region 38 during subsequent cooling becomes permanently bonded. Since the powder layer 18 is arranged directly on the build platform 14, this permanent bond is formed with the build platform 14. The melting can be carried out in such a way that the second selected region after a subsequent cooling has a second metallurgical structure, wherein the second metallurgical structure differs from the first metallurgical structure.

[0184] Subsequently, the control apparatus 34 lowers the build platform 14 by a predetermined distance which corresponds to the height of a further powder layer 18 to be subsequently applied. For this further powder layer 18, too, the first process gas is introduced and a first selected region of the further powder layer is melted, and/or the second process gas is introduced and a second selected region of the powder layer is melted. These steps can be repeated as required until the component has been completely produced layer-by-layer. In the process, each further molten layer or regions0 thereof, during subsequent cooling, forms a permanent bond with the layer located directly underneath.

[0185] Since the process gas used as protective gas has an influence on the phase transformation of a metal alloy, but does not interact significantly, if at all, with the metal powder or with the solidified component, the process gas is changed within a build job, preferably within a build plane, in order to achieve different properties in different regions of the build job or of the build plane. Expediently, scan vectors/regions to be selectively melted on a build plane having the same target property are collectively exposed by means of the laser, since a change of process gas takes longer than a change from one scan position to the next.

[0186] In addition to the use of discrete process gases, these can also be continuously mixed with varying composition. This allows, for example, graded materials to be produced. In particular, steels can be carburized using carbon-releasing process gases and the austenite proportion can be increased by nitrogen or nitrogen-containing atmosphere as opposed to purely inert process gases. A low proportion of oxygen in the process gas (a few percent) can reduce the proportion of carbon by means of oxidation. Using hydrogen-containing atmosphere, especially in the case of aluminium, can generate a porosity in the material in a controlled manner depending on the hydrogen content. This is based on the fact that the solubility of hydrogen in aluminium in the liquid state is markedly higher than in the solid state. On solidification, the no longer soluble hydrogen is expelled in the form of small pores. Depending on the original partial pressure of hydrogen in the process gas atmosphere, or dissolved in the aluminium melt, large or small pores, or even no pores, are formed.

[0187] The method can be modified as follows.

[0188] During the melting of the first selected region and/or of the second selected region, a pressure in the process chamber can be varied.

[0189] During the melting of the first selected region and/or of the second selected region, the applied layer can be at least partially heat treated. Alternatively or additionally, the method can furthermore comprise at least partially heat treating the applied layer after that of the first selected region and/or of the second selected region. For example, the heat treatment can be effected by means of a defocused laser. The first process gas and/or the second process gas can be introduced into the process chamber in such a way that a laminar gas flow above the applied powder layer is generated. Furthermore, a glass plate can be arranged at a predetermined distance from the applied powder layer, the predetermined distance being in a range from 0.5 mm to 20.0 cm and preferably from 1.0 cm to 10.0 cm. The laser can oscillate during the melting of the first selected region and/or of the second selected region. The melting of the first selected region and/or of the second selected region can be carried out in such a way that the first selected region and/or the second selected region are at least partially melted again. A power and/or a focus of the laser can be varied during the melting of the first selected region and/or of the second selected region.

[0190] FIG. 2 shows a Schaeffler diagram for chromium-nickel steels. The chromium equivalents form the abscissa and the nickel equivalents form the ordinate of the diagram. By means of the diagram, points in the diagram can be depicted for steels and cast irons. The nickel equivalent is calculated from the proportions by mass of the alloying elements which in the case of iron result in austenite being present in the microstructure. The chromium equivalent represents the efficacy of the ferrite-forming elements. The Schaeffler diagram is divided into different regions that represent the microstructure present. A point can be plotted in the Schaeffler diagram for each material. Depending on the location of the point, inter alia conclusions can be drawn concerning the microstructure present. The regions of the microstructure are austenite (A), martensite (M), ferrite (F) and transition regions for these microstructures indicated by (F+M), (A+M), (M+F) (A+M+F) and (A+F).

[0191] The Schaeffler diagram shown in FIG. 2 illustrates for steel materials, i.e. chromium-nickel steels, the influence of various alloying elements on the microstructure formation under welding-typical cooling conditions. The Schaeffler diagram was originally developed to allow a choice of welding electrodes to be made for various materials to be welded. The Schaeffler diagram makes it possible to estimate the effects of various welding additives on the developing microstructure during welding. Various alloying elements having a similar influence on the austenite formation, such as for example Ni, C, N, Mn, and on the formation of a ferritic microstructure, such as for example Cr, Mo, Si, Ta, Nb, Ti, are combined in the Schaeffler diagram as nickel equivalent or chromium equivalent, respectively. For example, an increase in the nickel equivalent by 8% can suppress the development of martensite and promote the formation of room temperature-stable austenite, as can be seen by the arrow 40. An increase in the chromium equivalent by 6% can likewise prevent the development of martensite and in contrast bring about the formation of a ferritic microstructure, as can be seen by the arrow 42.

[0192] The strong influence of nitrogen on the nickel equivalent is evident in the Schaeffler diagram by the factor 7.5. Other diagrams known from the prior art, such as for example the DeLong diagram, even indicate a factor of 30 for the influence of nitrogen. This means that for the abovedescribed shift along the arrow 40 the nitrogen proportion in an alloy only needs to be increased by a proportion of less than 1%.

[0193] In order to be able to significantly modify the developing microstructure of an alloy by a minor change in nickel or chromium equivalent, it is necessary for the alloy composition of the starting powder to be close to a boundary region in the Schaeffler diagram. This is illustrated by the plotted alloys along the arrows 40 and 42 in the Schaeffler diagram. Various methods can be used in this case to achieve a particular alloy composition. Firstly, a base material having the desired alloy composition may be atomized directly. Secondly, pre-atomized powders of various alloys may be mixed or supplemented with particular elemental powders. Here, however, sufficient mixing of the powders should be ensured in order to achieve a uniform chemical composition within a build job.

[0194] FIGS. 3A and 3B each show an enlarged section of a component having different microstructures. FIG. 3A shows the component having a ferritic core 44 and an austenitic shell 46 or surface surrounding the core 44. FIG. 3B shows the component having a ferritic core 44 and a martensitic shell 48 or surface surrounding the core 44. FIGS. 3A and 3B show how various microstructure regions may be used to set particular component properties. For example, the ferritic core 44 of a component can serve for achieving a high strength especially in the event of static mechanical loading. If a resistance to the influence of media is required, this can be done by establishing an austenitic microstructure at the surface. As protection against abrasion or for the achievement of internal compressive stresses in the surface, a formation of the hardened microstructure martensite may be desirable. Internal compressive stresses represent a possibility for improving the fatigue strength for components under cyclical loading. In addition, a controlled adjustment of a DP steel (dual-phase steel) having a ferritic basic matrix and strength-increasing martensitic regions distributed in island-like fashion can achieve specific properties of the material.

[0195] FIG. 4 shows a further apparatus 10 for producing a component by means of an additive manufacturing method using a laser. Hereinbelow, merely the differences from the apparatus shown in FIGS. 1A to 1D are described, and identical or comparable components are provided with identical reference numerals. The further apparatus 10 of FIG. 4 has a printhead 50 for applying or introducing an alloying element onto or into the powder layer 18 on the build platform. The alloying element can in particular be applied or introduced in the form of a suspension onto or into the powder layer 18. The further apparatus can furthermore comprise an actuator 52 which is designed for jointly moving the application apparatus 16 and the printhead 50.

[0196] With the apparatus 10 of FIG. 4, the method disclosed can be designed in such a way that a metal powder is provided, a powder layer 18 of the metal powder is applied to the build platform 14 and, in addition to the powder layer 18, at least one alloying element is applied or introduced, especially in the form of a suspension, onto or into the applied powder layer in at least one selected region 54. The applied powder layer 18 is subsequently melted by means of the laser. These steps can be repeated multiple times. It is explicitly emphasized that the apparatus shown in FIG. 4 can be realized separately from or in combination with the apparatus shown in FIGS. 1A to 1D. It is likewise explicitly emphasized that the method described in connection with FIGS. 1A to 1D, including modifications, can be carried out in combination with the method described in connection with FIG. 4 or separately therefrom.

[0197] The explanations hereinbelow apply equally both to the method described in connection with FIGS. 1A to 1D and to the method described in connection with FIG. 4.

[0198] By changing the process gas, the chemical composition of the material is modified in a spatially delimited manner in particular by the following proportions. An increase in the carbon proportion by up to 1.0%, in particular 0.2%, more particularly 0.08% and yet more particularly 0.03% can be realized via CO.sub.2 or CO. To increase the carbon content, in particular process gases having a CO.sub.2 proportion of from 100% down to 20% or in particular down to 5% and especially in the case of high alloy steels down to 2%, can be used in order to set the desired effect.

[0199] A reduction in the carbon content is possible by means of oxygen-containing process gases having an oxygen content of up to 15%, in particular an oxygen content of up to 5%, especially an oxygen content of 2%. The reduction in the carbon proportion here is in particular up to 70%, especially up to 30% of the initial content.

[0200] Nitrogen oxides NOx may also be used as process gases. This can simultaneously increase the nitrogen content and reduce the carbon content. This is of interest in particular when the intention is to influence the hardenability and the maximum achievable hardness.

[0201] An increase in the nitrogen content can be effected both by nitrogen of technical grade purity and by mixtures of nitrogen with inert gases, such as for example helium, argon, or other active gases, such as for example CO.sub.2, CO. The nitrogen proportion here may optionally be up to 100%, preferably up to 20% and in particular up to 2%.

[0202] The nitrogen proportion in the material in the process changes preferably by up to 0.6%, in particular up to 0.2%, especially in particular up to 0.05% and by a minimum of 0.01%, in particular

[0203] by a minimum of 0.03% and especially 0.08%.

[0204] Not all alloying elements are expediently convertible into a gaseous state or usable as such in the process. In order to modify the chemical composition by means of such elements, alloying elements can also be used in the solid state as described above. For improved meterability of the alloying elements in the printhead, these can in particular be printed in the form of a suspension. The materials used here are in particular chromium, silicon, molybdenum and titanium and possibly carbon, for example in the form of graphite. Chemical compounds with these elements, such as for example oxides, carbides or nitrides, are optionally also applicable, possibly also as a solution.

[0205] The powders which are applied with a printhead, especially in the form of a suspension, have a particle size which is far below the size of the material particles applied with the doctor blade, which have a size of approx. 10-100 m. The size of the particles applied by the printhead is in particular of the magnitude of below 10 m, in particular below 3 m and more particularly below 1 m.

[0206] The proportions of the mentioned alloying elements that are applied with the printhead are, proportional to the mass of the materials applied by the doctor blade, only up to at most 20%, in particular at most 7% and more particularly up to at most 2%.

[0207] Starting materials based on iron are in particular composed correspondingly:

[0208] At least 55%, in particular at least 75%, at most 99%, in particular at most 80% iron.

[0209] Preferably at least 1%, in particular at least 10% and at most 24% nickel.

[0210] Preferably at least 1% chromium, in particular at least 8% chromium and at most 35% chromium.

[0211] Additional alloying elements are typically: carbon, molybdenum, manganese, copper, tungsten, vanadium, silicon, tantalum, niobium and titanium.

[0212] The elements nitrogen and optionally carbon can on the one hand be greatly reduced in the starting material in order to achieve a large modification of the microstructure properties by addition of these elements in the SLM process (SLMselective laser melting). The nitrogen proportion and the carbon proportion can be limited to 0.1%, in particular 0.04%, more particularly to up to 0.01%. On the other hand, already relatively high nitrogen and carbon contents of for example 0.2% in the starting material may be used and these then reduced locally in the process.

[0213] FIG. 5 shows a side view of a further apparatus 10 for producing a component by means of an additive manufacturing method using a laser. FIG. 6 shows a top view of the apparatus 10 of FIG. 5. Hereinbelow, merely the differences from the apparatus shown in FIGS. 1A to 1D are described, and identical or comparable components are provided with identical reference numerals. The apparatus 10 of FIGS. 5 and 6 has a sealing slide 56. The sealing slide 56 is arranged within the process chamber 12. The sealing slide 56 is arranged above the build platform 14. The sealing slide 56 serves as a lateral delimitation and therefore laterally contacts the walls of the process chamber 12. The sealing slide 56 is movable relative to the build platform 14. Thus the sealing slide 56 is movable in particular parallel to the build platform 14. In addition, a first connection or inlet 58 of the first process gas source 30 into the process chamber 12 and a first outlet 60 for the first process gas out of the process chamber 12 are illustrated. In addition, a second connection or inlet 62 of the second process gas source 32 into the process chamber 12 and a second outlet 64 for the second process gas out of the process chamber 12 are illustrated. The first inlet 58 and the first outlet 60 lie opposite each other. The second inlet 62 and the second outlet 64 lie opposite each other. The first inlet 58 and the first outlet 60 and the second inlet 62 and the second outlet 64 are situated on different sides of the sealing slide 56. In other words, the sealing slide 56 is arranged in the manner of a sandwich between the first inlet 58 and the first outlet 60 on one side and the second inlet 62 and the second outlet 64 on the other. During operation of the apparatus 10, the laser of the laser source 22 penetrates from above through a laser protection glass (not shown in more detail) into the process chamber 12 in order to expose the uppermost powder layer 18 on the build platform 14. The movable sealing slide 56 seals against the laser protection glass and the powder layer 18. A change between the first process gas and the second process gas is effected by moving the sealing slide 56, which when moved permits admission of one process gas and displacement of the process gas to the corresponding outlet of the other process gas. In the case of the exemplary position of the sealing slide 56 in FIG. 6, the process chamber 12 is completely flooded with the second process gas, while the sealing slide 56 displaces the first process gas towards the outlet 60. The sealing slide 56 in the process ensures separation of the process gases.

[0214] The aim of the apparatus 10 is to realize differing material and alloying states in a layer plane. To this end, gas changes are required not only once, but multiple times, for example more than 100 gas changes, over the entire process duration. One problem with this is that a large gas volume in the system always has to be exchanged. On account of the large gas volume, the system is sluggish and a change takes a very long time, for example a few minutes. Since the gas change takes place by way of a displacement with the new process gas, this is accompanied by high gas consumption and high costs. The apparatus of FIGS. 5 and 6 offers a solution by means of the use of at least two gas chambers each optionally having a dedicated recirculation and treatment unit (gas filter). The sealing surfaces are the glass plate or laser protection glass and also a lower and lateral sealing delimitation which can be displaced over the powder bed. This sealing delimitation is realized by the movable sealing slide 56. With this, the surface of the powder bed can be exposed to different gases without these mixing and having to be exchanged in a laborious manner in the overall recirculation system.

[0215] FIGS. 7A to 7C show top views of a further apparatus 10 for producing a component by means of an additive manufacturing method using a laser in various operating states. Hereinbelow, merely the differences from the apparatus shown in FIGS. 5 and 6 are described, and identical or comparable components are provided with identical reference numerals. In the apparatus 10 shown in FIGS. 7A to 7C, the sealing slide 56 is connected to the application apparatus 16 by means of a frame 66. The application apparatus 16 is movable relative to the build platform 14. Thus the application apparatus 16 is movable in particular parallel to the build platform 14. Accordingly, the sealing slide 56 is movable integrally/together with the application apparatus 16 relative to the build platform 14. Thus the sealing slide 56 is movable in particular parallel to the build platform 14. The application apparatus 16 is for example a movable doctor blade. In the apparatus 10 shown in FIGS. 7A to 7C, during operation the entire frame 66 is displaced along with the doctor blade movement or the movement of the application apparatus 16, so that the supply of gas can always be effected centrally through a nozzle. The connections or inlets 58, 62 for the first process gas and the second process gas and any further process gases are designed to be flexible so that they can follow the movement of the frame 66. The sealing slide 56 and the doctor blade or application apparatus 16 for applying the powder to the build platform 14 are situated in the centre. FIGS. 7A to 7C show the two positions/locations of the frame 66 with sealing slide 56 for the sole use of the first and second process gas and also an intermediate position during the movement of the frame 66 or application apparatus 16 or during the gas change. In the exemplary position of the frame 66 or sealing slide 56 in FIG. 7A, the process chamber 12 is completely flooded with the second process gas, while the sealing slide 56 displaces the first process gas towards the first outlet 60. In the exemplary position of the frame 66 or sealing slide 56 in FIG. 7B, the process chamber 12 is the sealing slide 56 is situated approximately in the centre of the build platform or of the powder layer 18 located thereupon, so that the process chamber 12 is flooded with the first process gas on one side of the sealing slide 56 and is flooded with the second process gas on the other side of the sealing slide 56. In the exemplary position of the frame 66 or sealing slide 56 in FIG. 7C, the process chamber 12 is completely flooded with the first process gas, while the sealing slide 56 displaces the second process gas towards the second outlet 64. The sealing slide 56 thus ensures separation of the process gases.