Additive metal powder bed manufacturing method for a predetermined texture by irradiation according to a dot pattern

Abstract

The invention relates to an additive manufacturing method in which a layer produced from a metal powder forms an xy-construction plane which is solidified by means of an energy beam by producing melting points, an additional layer applied to the layer in the z-direction and produced from the metal powder forms an additional xy-construction plane which is solidified by producing additional melting points such that, by repeating the aforementioned steps, a component having a predetermined shape is formed from the solidified layers, wherein, in order to produce a predetermined texture in the component from the crystal structure of the metal used to produce the metal powder, (a) a 2-dimensional dot pattern for the xy-construction plane is determined, and (b) a rule for determining a spatial relationship between the 2-dimensional dot pattern and at least one additional 2-dimensional dot pattern in the at least one additional xy-construction plane is defined, the melting points in the xy-construction plane are produced according to the 2-dimensional dot pattern, and the additional melting points in the additional xy-construction plane following in the z-direction are produced according to an additional 2-dimensional dot pattern which results from applying the rule.

Description

[0001] Additive manufacturing process

[0002] The invention relates to an additive manufacturing process according to the preamble of claim 1.

[0003] Such a process is known, for example, from EP 3 482 853 A1. In this process, a layer made from a metal powder forms an xy-plane. The xy-plane is solidified by means of an energy beam through the creation of melting points. A further layer of the same metal powder, following in the z-direction, forms another xy-plane. This further xy-plane is solidified by the creation of additional melting points and bonded to the layer below. The melting points and subsequent melting points are staggered. The additional melting points solidify areas in the layer below that are not fully solidified.

[0004] Additive manufacturing has the disadvantage that, due to solidification oriented in the build direction (or z-direction), columnar crystals often form, extending in the build direction. This results in an anisotropic texture, which can be detrimental, for example, in mechanical terms. To overcome this disadvantage, the wall thickness of a component must be increased, at least in certain areas. This, in turn, increases the weight and manufacturing effort.

[0005] To improve the mechanical properties in particular, attempts are made to create an isotropic texture with small crystallites. It is known to add alloying elements that act as nucleation sites for this purpose. While this can alter the texture, it also changes the alloy itself, which is often undesirable.

[0006] From A. Plotkowsski, et al., A stochastic scan strategy for grain structure control in complex geometries using electron beam powder bed fusion, Additive manufacturing 46 (2021) 102092, it is known that a relatively large melting zone or melt pool can be produced by a high energy input. This enables a CET (columnar to equitaxed transition) and thus influences the texture. However, it requires a high energy input. This, in turn, necessitates the production of walls with a certain minimum thickness. The resulting texture is usually not completely isotropic.

[0007] It is also known that the texture can be influenced by the arrangement of melting points and / or melting lines (Dehoff et al.; Site specific control of crystallographic grain orientation through electron beam additive manufacturing, Materials Science and Technology 31 (8) 2015 931 -938).

[0008] The object of the invention is to eliminate the disadvantages of the prior art. In particular, it aims to provide an efficient additive manufacturing process for producing metallic components with a predetermined texture. Advantageously, the predetermined texture should only be producible in specific areas of the component. A further objective is to provide a device for carrying out the process.

[0009] The problem is solved by the features of claims 1 and 24. Advantageous embodiments result from the dependent claims.

[0010] According to the invention, in an additive process, it is proposed that a predetermined texture in the component is produced from the crystal structure of the metal used to produce the metal powder.

[0011] (a) determines a 2-dimensional point pattern for the xy-plane and

[0012] (b) a rule for determining a spatial relationship between the 2-dimensional point pattern and at least one further 2-dimensional point pattern in the at least one further xy-plane, the melting points in the xy-plane are produced according to the 2-dimensional point pattern, and the further melting points in the further xy-plane following in the z-direction are produced according to a further 2-dimensional point pattern which results from applying the rule.

[0013] The proposed method enables the particularly simple and cost-effective production of metallic components with a predefined texture. Furthermore, the texture can be adjusted within the component itself, depending on the specific requirements. This allows, for the first time, comprehensive material design of a component. The component's texture can be optimized, for example, with regard to its mechanical properties. Areas within the component can be created with isotropic textures and other areas with anisotropic textures. This makes it possible to optimally adapt the component to specific mechanical stresses, for example. This results in material savings and the production of lightweight components. Similarly, components with textures can also be manufactured to achieve predefined electrical, magnetic, or thermo-mechanical properties.

[0014] The proposed method requires no changes to the alloy, no particularly high energy input, and no use of crystal seeds. It is based solely on the surprising discovery that by arranging the melting points in a way that corresponds to the crystal structure of the respective metal, a predetermined texture can be produced in the component.

[0015] Definitions

[0016] A microstructure, or structure, describes the arrangement and order of the constituents at the visible and microscopic level, regardless of the material (metal, ceramic, or polymer). The microstructural constituents, such as crystallites or grains, fillers, and amorphous regions, are typically very small and can be visualized qualitatively and quantitatively, for example, using a light microscope.

[0017] Texture refers to the totality of orientations of the crystallites in a given section of the produced polycrystalline solid.

[0018] An anisotropic texture refers to a polycrystalline solid in which the crystallites exhibit at least one preferred orientation. The preferred orientation is indicated by the direction of the surface normals according to the Miller indices.

[0019] Isotropic texture refers to a multicrystalline solid in which the crystallites do not exhibit a preferred orientation.

[0020] The term crystal structure refers to the crystal structure that forms during the solidification of a metal or alloy. The crystal structure is a three-dimensional periodic repetition of the basis (or a motif). Vectors that coincide with a lattice are called translation vectors t. They form a translationally symmetric point lattice. The points of this lattice do not represent atoms; they merely describe the periodicity of the crystal structure.

[0021] In the present invention, a translation vector t defines the displacement of superimposed point patterns in space. From the translation vector t, a displacement vector can expediently be determined by projecting the superimposed point patterns. This displacement vector extends along the xy-plane and describes only the displacement of the superimposed point patterns in the respective xy-planes.

[0022] A unit cell is the parallelepiped formed by three basis vectors. In metals, the unit cell exhibits either cubic or hexagonal symmetry. In this case, the unit cell can also be described as a "primitive unit cell". The basis vectors a v , b v , c vThe parameters are chosen such that the lattice they form corresponds to the lattice of a crystal. The coordinates of the crystal's lattice points are integers. The lattice is a geometric representation of a real crystal lattice. The distances between adjacent points in the unit cell are determined according to the basis vectors a. v , bv, c v Designated a, b, c, these are fictitious distances chosen in the invention to correspond to the distances between adjacent points in the two-dimensional dot pattern. A real crystal lattice is formed by atoms. The distance between atoms depends on several parameters, such as the size of the atoms involved. x, y, z directions: directions used to describe additive manufacturing or the manufacturing equipment. The xy directions describe the horizontal xy build planes, while the z direction is perpendicular to the xy build planes and describes the build direction or build height.

[0023] According to an advantageous embodiment of the invention, to produce an anisotropic texture, a spatial arrangement of the melting points in the superimposed xy-planes is chosen such that they correspond to the symmetry of the unit cell.

[0024] To determine the two-dimensional dot pattern, a unit cell of the crystal structure can be oriented relative to the z-direction according to the texture to be produced. One of the basis vectors a is used. v , b v , c v chosen and the points of intersection of parallel to the basis vector a are selected. v , b v , c v The oriented straight lines are determined using the xy-plane. The basis vector is a. v , b v , c v The basis vector a will be used expediently. v , b v , c vThe line with the largest component in the z-direction is chosen. The relative positions of the lines are determined by the unit cell. The distances between the lines are determined by the other basis vectors a. v , b v , c v This defines a family of parallel lines that intersect the xy-construction planes. The points of intersection define the location of the melting points to be produced. The "rule for determining a spatial relationship between the 2-dimensional point pattern" can be given by a translation vector t, which determines the spatial position of the superimposed 2-dimensional point patterns relative to each other. The translation vector t extends parallel to the chosen basis vector a. v , b v , c vThe magnitude of the translation vector t can be determined as a function of the thickness d of the layers. Using such a translation vector t, the position of the melting points in the superimposed layers can be calculated quickly and easily as a function of the thickness d of the layers.

[0025] Especially in the production of <110> or <111> Textures can be used when a predetermined value for the translation vector t is reached, with another translation vector t1 having a changed direction, where the changed direction is parallel to one of the other basis vectors a v , b v , c v This is the case. By changing the direction of the translation vector in this way, the spatial symmetry can be improved.

[0026] According to a first simple embodiment of the invention, the 2-dimensional dot pattern can exhibit quadratic point symmetry, wherein the points have a first distance A1, where A1 = a. To form a <100> In this case, the texture in the z-direction is the translation vector t aligned parallel to the z-direction.

[0027] According to a second, simpler variant, the 2-dimensional point pattern can exhibit rectangular point symmetry, where the points have a first distance A1 in a first direction and a second distance A2 in a second direction, where A2 = 2a. To form a <110> In this case, the texture in the z-direction is formed by the translation vector t inclined at 45° to the z-axis.

[0028] According to a third simple variant, the 2-dimensional dot pattern can exhibit hexagonal point symmetry, with adjacent points of the hexagon having a distance of the second A2. To form a texture, the translation vector t in the z-direction is inclined in this case by 50° to 60°, preferably by 53° to 57°, and particularly preferably by 54.7°, relative to the z-axis.

[0029] In addition to the simple variants shown above, a variety of other variants can be implemented - depending on requirements - by choosing a unit cell and its orientation relative to the z-axis.

[0030] Advantageously, in a symmetrical two-dimensional dot pattern, the radius r of a melting point is chosen to be smaller than the smallest of the distances to the next-but-one melting point. This ensures sufficient hardening of the layers. At the same time, this allows the desired texture to be created.

[0031] A particular advantage of the method according to the invention is that the production of melting points according to a symmetrical two-dimensional dot pattern can be carried out with minimal effort in at least one predetermined surface area of ​​the xy-plane. It is only necessary to produce the melting points according to the selected two-dimensional dot pattern in the predetermined surface area. A different texture can be produced in an adjacent surface area using the method according to the invention.

[0032] An isotropic texture can also be produced according to the inventive method. For the production of an isotropic texture, an asymmetrical dot pattern deviating from the symmetry of the unit cell is advantageously selected as the 2-dimensional dot pattern. This prevents the random formation of symmetrical arrangements of melting points. A nearly completely isotropic texture can be produced reliably and safely. With conventional additive manufacturing processes, the production of nearly completely isotropic textures is either impossible or extremely difficult. Conventionally produced isotropic textures are usually incomplete, meaning that areas with undesirable anisotropic textures remain. To produce the asymmetrical 2-dimensional dot pattern, the points of a symmetrical 2-dimensional dot pattern can be stochastically shifted by a fraction of the distance A1, A2.Alternatively, a different 2-dimensional dot pattern can be chosen, which differs from the asymmetrical 2-dimensional dot pattern.

[0033] It has proven advantageous to create an isotropic texture by choosing a larger radius r of the melting points in the respective xy-point pattern than the distance to the next-but-one neighboring point. Using the above measures, an isotropic texture can be reliably and safely generated across the desired volume.

[0034] In the method according to the invention, an electron beam or a laser beam can be used as the energy beam. The distances A1, A2 between the adjacent points in the xy plane are advantageously 50 to 500 pm.

[0035] The unit cell is advantageously a cubic, face-centered cubic, body-centered cubic or hexagonal unit cell.

[0036] The method described herein can be carried out using an additive manufacturing device for metallic components, which is configured for this purpose. The device may include a computer equipped with a program for controlling the energy beam, such that the melting points are produced according to the previously calculated two-dimensional point patterns.

[0037] General examples

[0038] A method for producing a specified anisotropic texture, using a specified metal or alloy, may, for example, be carried out by the following steps: (i) determining the desired texture.

[0039] (ii) Selection of the unit cell of the metal or alloy.

[0040] (iii) Determining the position of the unit cell relative to the z-direction.

[0041] (iv) Selection of a basis vector a v , b v , cv of the unit cell. Preferably, the basis vector a v , b v , c v selected with the largest component in the z-direction.

[0042] (v) Determination of distances and the position of lines parallel to the basis vector a v , b v , CV-oriented.

[0043] (vi) Determination of a 2-dimensional point pattern by identifying the points of intersection of the lines with an xy-planar plane.

[0044] (vii) Optional: Specifying a displacement vector to determine the position of another 2-dimensional point pattern in another xy-plane relative to the symmetric 2-dimensional point pattern.

[0045] To determine the position of the unit cell, in particular its rotation angle around the z-axis and the angle of an edge with respect to the z-axis are specified.

[0046] To generate the symmetrical two-dimensional dot pattern for the melting points, the point spacing or the distances between the lines can be appropriately chosen. In simple cases, the symmetrical two-dimensional dot pattern may also be known beforehand.

[0047] The distance between two melting points is typically between 50 and 500 pm. The radius of a melting point is usually between 50 and 300 pm. The distance d between two successive xy-planes is typically between 50 and 100 pm. The displacement vector conveniently describes the relative displacement of the melting points in directly superimposed planes. Its magnitude depends on the distance d between the xy-planes. To generate a further symmetrical 2-dimensional point pattern, the displacement vector can be used, for example, to shift the symmetrical 2-dimensional point pattern by a predetermined amount in the x- and / or y-direction.

[0048] Exemplary embodiments of the invention are explained below with reference to the drawing. The drawing shows:

[0049] Fig. 1 shows a cubic unit cell and a first projection into an xy-plane.

[0050] Fig. 2 shows a cubic unit cell and a second projection into an xy-plane.

[0051] Fig. 3. the cubic unit cell according to Fig. 2 and projections into several xy-planes,

[0052] Fig. 4 shows a cubic unit cell and a third projection into an xy-plane.

[0053] Fig. 5 shows a hexagonal unit cell and a fourth projection into an xy-plane.

[0054] Fig. 6 shows a top view of an xy-plane with a transition from the projection of a cubic unit cell to a hexagonal unit cell.

[0055] Fig. 7 is a projection of the cubic unit cell onto the xy-plane, wherein the cubic unit cell is tilted in the

[0111] direction, Fig. 8 is the projection according to Fig. 7, wherein the cubic unit cell tilted in the

[0111] direction is additionally rotated about the x-axis by 11.8 degrees (rotation about the y-axis is equal to 0 degrees),

[0056] Fig. 9 shows the projection according to Fig. 7, where the rotation about the x-axis is 23.5 degrees (rotation about the y-axis is equal to 0 degrees).

[0057] Fig. 10 shows the projection according to Fig. 7, where the rotation about the x-axis is 35.3 degrees (rotation about the y-axis is equal to 0 degrees).

[0058] Fig. 11 shows a projection of a cubic unit cell tilted in the

[0111] direction, which is tilted about the x-axis by 35.3 degrees and about the y-axis by 22.5 degrees,

[0059] Fig. 12 shows a projection of a cubic unit cell tilted in the

[0111] direction, with rotation about the x-axis being 35.5 degrees and rotation about the y-axis being 45 degrees,

[0060] Fig. 13 shows a first pole diagram, and

[0061] Fig. 14 shows a second pole diagram, and

[0062] Fig. 15 shows a third pole diagram.

[0063] production of a <100> Texture in the z-direction or building direction (see Fig. 1)

[0064] To manufacture a component from a metal with cubic symmetry, a point pattern with quadratic point symmetry is chosen as the two-dimensional point pattern. Such a point pattern is generally known and does not need to be determined by intersecting the xy-plane with the unit cell. The points have a first spacing A1 in the x and y directions, where A1 = a. A suitable distance is chosen for a. This distance corresponds to the spacing of the melting points. This results in a symmetrical two-dimensional point pattern for creating the melting points in the xy-plane. To create another two-dimensional melting point pattern in the next xy-plane, the previously generated symmetrical two-dimensional melting point pattern can be used. It is created in the next xy-plane in the z-direction in an identical arrangement, where n denotes the normal vector.In this simple case, the displacement vector is zero, since there is no displacement of the 2-dimensional point pattern in the next xy-plane in the x- and / or y-direction. Continuing these steps results in a component where the crystals have a predominant orientation in the z-direction. <100> exhibit texture.

[0065] production of a <110> Texture in the z-direction or building direction (see Fig. 2)

[0066] To manufacture a component from a metal with cubic symmetry, a point pattern with rectangular point symmetry is chosen as the two-dimensional point pattern. The points in the y-direction have a first spacing A1 and in the x-direction a second spacing A2, where A2 = 2a. Such a point pattern is generally known; it does not need to be determined by an intersection of the xy-plane with the unit cell. This results in a symmetrical two-dimensional melting point pattern for creating the melting points in the xy-plane. n denotes the normal vector. To create another two-dimensional point pattern in the next subsequent xy-plane, the already generated symmetrical two-dimensional point pattern can be used. To generate the further two-dimensional point pattern, the melting points in the next xy-plane are shifted, for example, by a translation vector by a predetermined amount in the x- and / or y-direction.The specified amount depends on the distance d of the further xy-construction plane from the underlying xy-construction plane and the angle, here 45°, which the selected basis vector a. v , b v , c v with the z-direction.

[0067] In the further xy-plane, another 2-dimensional melting point pattern is created in the z-direction. This pattern is identical to the first 2-dimensional melting point pattern, but shifted relative to the first by the amount specified by the displacement vector in the x- and / or y-direction. Continuing these steps results in a component where the crystals in the z-direction predominantly form a <110> exhibit texture.

[0068] Fig. 3 shows the construction of several layers s, s+1 , s+2 using the 2-dimensional pattern shown in Fig. 2, t describes the translation vector, n the normal vector.

[0069] Figures 4 and 5 show two-dimensional point patterns analogous to Figures 1 and 2. Figure 4 shows a third projection into an xy-plane for a cubic unit cell, and Figure 5 shows a fourth projection into an xy-plane for a hexagonal unit cell.

[0070] Production of a <111 > texture in the z-direction or build direction (see Fig. 7)

[0071] To manufacture a component from a metal with cubic symmetry, a point pattern with hexagonal point symmetry is chosen as the two-dimensional point pattern. Adjacent points in the hexagon have a distance of A2 = 2a. Such a point pattern is generally known and does not need to be determined by intersecting the xy-plane with the unit cell. This results in a symmetrical two-dimensional point pattern for creating the melting points in the xy-plane.

[0072] To create another 2-dimensional point pattern in the next subsequent xy-plane, the already generated symmetrical 2-dimensional point pattern can be used. To generate the additional 2-dimensional point pattern, the points of the symmetrical 2-dimensional point pattern are shifted, for example, by a translation vector, by a predefined amount in the x- and / or y-direction. The predefined amount depends on the distance d of the additional xy-plane from the underlying xy-plane and the angle formed by the selected basis vector a. v , b v , c vwith the z-direction. This is inclined by 54.74 degrees relative to the x-, y-, and z-axes. In the further xy-construction plane, another 2-dimensional melting point pattern is created in the z-direction. This pattern is identical to the 2-dimensional melting point pattern, but is shifted in the xy-projection by an amount in the x- and y-directions determined by the translation vector t. Continuing these steps results in a component where the crystals predominantly exhibit a <111> texture in the z-direction.

[0073] In the process for manufacturing the <110> Texture can be the basis vector a v , b v , c v be inclined at +45° or -45° with respect to the z-direction. In the process for producing the <111> texture, the basis vector a v , b v , c vThey can be directed parallel to the three spatial directions of the cube's diagonals (Fig. 7). In these cases, one direction of the basis vector a can be v , b v , c v e.g., depending on the progress of construction, especially when a predetermined layer thickness is reached.

[0074] The proposed method allows the creation of textures with virtually any orientation. This is achieved by rotating the unit cell in space around the x- and / or y-axis. The resulting symmetrical two-dimensional point patterns can be determined by the intersection points of the respective unit cell with the xy-plane or computationally (see Figures 8 to 11).

[0075] A process for producing an isotropic texture can, for example, be carried out by the following steps:

[0076] (i) Selection of a unit cell of the metal or alloy.

[0077] (ii) Determining the position of the unit cell relative to the z-direction

[0078] (iii) Determination of at least one symmetric 2-dimensional point pattern by an intersection of the xy-planar plane with the unit cell, (iv) Transformation of the symmetric 2-dimensional point pattern into an asymmetric 2-dimensional point pattern, e.g. by stochastic translation of at least a subset of the points,

[0079] (v) Generating a further asymmetric point pattern for the next following xy-plane such that at least a further subset of the points of the further asymmetric point pattern are not congruent with the points of the symmetric point pattern in the z-direction.

[0080] The generation of the further asymmetric point pattern can be achieved, for example, by arranging its points in the gaps of the asymmetric point pattern in the z-direction in such a way that the formation of a 3-dimensional symmetry is avoided.

[0081] The generation of the further asymmetric point pattern can also be achieved, for example, by translating the asymmetric point pattern into a non-coincident position relative to the asymmetric point pattern using a translation vector t. Advantageously, the direction of the translation vector t is changed from one xy-plane to the next xy-plane, thus ensuring an asymmetric arrangement of the points in 3-dimensional space.

[0082] The generation of a specific texture using the proposed method can be limited to at least a predetermined volume fraction. Different textures can also be produced in different volume fractions. This allows, for the first time, specific properties to be set in components within predetermined volume fractions. These properties can include mechanical properties, such as stiffness in the direction of load, magnetic properties, vibration properties, and so on.

[0083] Electron Beam-Based Additive Manufacturing (PBF-EB) In the following embodiments, the nickel-based superalloy IN718 was processed using electron beam-based additive manufacturing (PBF-EB). The experiment was performed on a 15 kW PBF-EB system (PB-EBM 30S) from pro-beam GmbH & Co. KGaA (Gilching, Germany) at an accelerating voltage of 150 kV. The starting material used was a plasma-atomized powder of the nickel-based superalloy IN718 from Tekna Plasma Europe (Mäcon, France) with a particle size distribution between 45 pm and 105 pm. The chemical composition is listed in Table 1.

[0084] Table 1 Chemical composition of IN718 powder

[0085] The manufacturing process took place under a controlled, protective gas-free vacuum atmosphere at a pressure of 2x10' 5mbar. The process temperature was measured during manufacturing using a thermocouple attached to the underside of a base plate; a control system maintained a constant process temperature of 900 °C. Maintaining the process temperature was achieved primarily by a rapidly deflected and expanded electron beam during a preheating step. For the subsequent melting of the powder layer, the beam was focused to a full width at half maximum (FWHM) between 174 pm and 380 pm.

[0086] Texture analysis using electron backscatter diffraction (EBSD)

[0087] Electron backscatter diffraction (EBSD) is a microstructural crystallographic technique used in scanning electron microscopy (SEM) to determine the crystallographic orientation of materials. An electron beam is directed onto a tilted sample, causing backscattered electrons to form so-called Kikuchi patterns, which are detected by a phosphor screen detector. The Kikuchi patterns result from intersecting lines formed by constructive interference of the electrons scattered from the crystal lattice and satisfy Bragg's law. The Kikuchi patterns are analyzed to determine the crystal orientation at each scanned point.

[0088] EBSD provides detailed information about grain orientation, phase identification, and crystal structure. EBSD data were acquired using a NordlysNano detector from Oxford Instruments and visualized with AZTec software. Acceleration voltage was 20 kV, beam current 0.69 nA, and a step size of 5 pm with a sample tilt of 70°. EBSD data processing was performed using the open-source Matlab library MTEX. Orientation density function (ODF) polar figures were used to visualize textures. These represent the volume fraction of crystals in a polycrystalline sample AV(g) whose orientation g lies within a volume element dg of g relative to the total number of grains V in the measurement volume, according to equation (1).

[0089] ODF(g)= AV(g) / Vdg (Eq. 1 )

[0090] To make a quantitative comparison between the characteristics of different textures, the so-called texture index JODF is used according to equation (2).

[0091] JODF = f \ODF(g)\ 2 dg (Eq. 2)

[0092] A texture index of JODF = 1 indicates a completely random distribution of grain orientations within the measurement volume (= isotropy). The higher the JODF value, the more pronounced the respective texture.

[0093] Example of a <111> Texture in the build direction (see Fig. 7). For the creation of the xy-point pattern, a point spacing a = 200 pm was chosen. According to the rules of the invention, tilting the cubic unit cell by phi = 45° and theta = 35° (space diagonal of the cube in the build direction) results in a hexagonal point pattern with a point spacing of 282.84 pm. Furthermore, with a selected layer thickness d of 50 pm, a translation vector t = (35.36 pm, 61.24 pm, 50 pm) is obtained. The magnitude of the displacement vector in the xy-plane is 70.71 pm.

[0094] The individual points are melted at a point energy of 169 mJ, a point residence time of 308 ps and a beam half-width of approximately 170 pm.

[0095] Figure 13 shows the resulting texture as the first pole diagram or first ODF pole figure. A clear texture with threefold symmetry, corresponding to the dot pattern, can be observed. The JODF texture index is 1.67. The direction-dependent Young's modulus calculated from the ODF pole figure is 234 GPa in the build-up direction.

[0096] Example of a <100> Texture in the build direction (see Fig. 14). For the production of the xy-dot pattern, a dot spacing of a = 280 pm was chosen. The layer thickness d is 50 pm. According to the rules of the invention, tilting the cubic unit cell by phi = 0° and theta = 0° (surface normal of the cube in the build direction) results in a cubic dot pattern with a dot spacing of 280 pm. The translation vector is t = (0 pm, 0 pm, 50 pm). This results in a displacement vector in the xy-plane of (0 pm, 0 pm). The individual dots are melted at a dot energy of 261 mJ, a dot residence time of 348 ps, and a beam width at half maximum of approximately 380 pm.

[0097] In Fig. 14, the resulting texture is shown as the second pole diagram or second ODF pole figure. It is a clear <100> Texture is observed. The JODF texture index is 3.96. The direction-dependent Young's modulus calculated from the ODF pole figure is 129 GPa in the build-up direction. Example of an isotropic sample.

[0098] For the production of the xy-dot pattern, a dot spacing a = 141.4 pm was chosen. According to the rules of the invention, tilting the cubic unit cell by phi = 45° and theta = 35.3° (space diagonal of the cube in the build direction) results in a hexagonal dot pattern in the xy-build plane with a dot spacing AS2 = 200 pm. The translation vector t = (100 pm, 57.74 pm, 50 pm) chosen here differs significantly from the values ​​t = (35.36 pm, 61.24 pm, 50 pm) calculated according to the rules for the anisotropic case, each with a layer thickness of 50 pm.

[0099] The individual points are melted at a point energy of 65 mJ, a point residence time of 68 ps and a beam half-width of approximately 174 pm.

[0100] In Fig. 15, the resulting texture is shown as the third pole diagram or third ODF pole figure. The texture index JODF is calculated to be 1.03. A texture index of 1 indicates a completely random distribution of grain orientations in the measurement volume. The direction-dependent E-modulus calculated from the ODF is 202 GPa. This corresponds approximately to the literature value for IN718 in the isotropic state.

Claims

Patent claims 1. Additive manufacturing process in which a layer produced from a metal powder forms an xy-plane, which is solidified by means of an energy beam through the creation of melting points, a further layer produced from the metal powder and applied in the z-direction on the layer forms another xy-plane, which is solidified by the creation of further melting points, so that by repeating the aforementioned steps a component with a predetermined shape is formed from the solidified layers, characterized in that, in order to produce a predetermined texture in the component, the crystal structure of the metal used to produce the metal powder is used. (a) determines a 2-dimensional point pattern for the xy-plane and (b) a rule for determining a spatial relationship between the 2-dimensional point pattern and at least one further 2-dimensional point pattern in the at least one further xy-plane, the melting points in the xy-plane are produced according to the 2-dimensional point pattern, and the further melting points in the further xy-plane following in the z-direction are produced according to a further 2-dimensional point pattern which results from applying the rule.

2. Additive manufacturing process according to claim 1, wherein, for the production of an anisotropic texture, a spatial arrangement of the melting points in the superimposed xy build planes is selected such that they correspond to the symmetry of the unit cell.

3. Additive manufacturing process according to one of the preceding claims, wherein, to determine the 2-dimensional dot pattern, a unit cell of the crystal structure is oriented relative to the z-direction according to the texture to be produced, one of the basis vectors a v , b v , c v is chosen and the intersection points of parallel to the basis vector a v , b v , c v The oriented lines are determined using the xy-planar plane, whereby the relative positions of the lines are determined by the unit cell and the distances between the lines are determined by the further basis vectors a v , b v , c v be defined.

4. Additive manufacturing process according to claim 3, wherein a is the basis vector. v , b v , c v the basis vector a v , b v , c v The one chosen is the one with the largest component in the z-direction.

5. Additive manufacturing process according to one of the preceding claims, wherein the rule is given by a translation vector t which determines a position of the superimposed 2-dimensional point patterns relative to each other.

6. Additive manufacturing process according to one of the preceding claims, wherein one direction of the translation vector t is parallel to the selected basis vector av, bv, Cv.

7. Additive manufacturing process according to one of the preceding claims, wherein an amount of the translation vector t is determined as a function of a thickness d of the layers.

8. Additive manufacturing process according to one of the preceding claims, wherein upon reaching a predetermined value for the translation vector t a A further translation vector t1 with a changed direction is used, where the changed direction is parallel to one of the further basis vectors a v , b v , c v is.

9. Additive manufacturing process according to one of the preceding claims, wherein the 2-dimensional dot pattern has a square point symmetry, wherein the points have a first distance A1, wherein A1 = a.

10. Additive manufacturing process according to one of the preceding claims, wherein for the formation of a <100> The texture in the z-direction is aligned with the translation vector t parallel to the z-direction.

11. Additive manufacturing process according to one of the preceding claims, wherein the 2-dimensional dot pattern has a rectangular point symmetry, wherein the points have a first distance A1 in a first direction and a second distance A2 in a second direction, wherein A2 = 2a.

12. Additive manufacturing process according to one of the preceding claims, wherein for the formation of a <110> The texture in the z-direction has the translation vector t inclined at 45° to the z-axis.

13. Additive manufacturing process according to one of the preceding claims, wherein the 2-dimensional dot pattern has a hexagonal point symmetry, wherein adjacent points of the hexagon have the second distance A2.

14. Additive manufacturing process according to one of the preceding claims, wherein, to form a <111 >texture in the z-direction, the translation vector t is inclined relative to the z-axis by 50° to 60°, preferably by 53° to 57°, particularly preferably by 54.7°.

15. Additive manufacturing process according to one of the preceding claims, wherein in the symmetrical 2-dimensional dot pattern a radius r of a The melting point is chosen to be smaller than the smallest of the distances to the next-but-one melting point.

16. Additive manufacturing process according to one of the preceding claims, wherein the production of the melting points according to a symmetrical 2-dimensional dot pattern takes place only in at least one predetermined surface section of the xy build plane.

17. Additive manufacturing process according to one of the preceding claims, wherein an asymmetric dot pattern deviating from the symmetry of the unit cell is selected to produce an isotropic texture as a 2-dimensional dot pattern.

18. Additive manufacturing process according to one of the preceding claims, wherein, to produce the asymmetric 2-dimensional dot pattern, the points of a symmetric 2-dimensional dot pattern are stochastically shifted by a fraction of the distance a.

19. Additive manufacturing process according to claim 18, wherein a further 2-dimensional dot pattern is selected which differs from the asymmetric 2-dimensional dot pattern.

20. Additive manufacturing process according to one of the preceding claims, wherein, in order to form an isotropic texture, the radius r of the melting points in the respective xy-point pattern is chosen to be larger than the distance to the next-but-one neighboring point.

21. Additive manufacturing process according to one of the preceding claims, wherein an electron beam or a laser beam is used as the energy beam.

22. Additive manufacturing process according to one of the preceding claims, wherein the distances between the adjacent points in the xy-plane are 50 to 500 pm.

23. Additive manufacturing process according to any of the preceding claims, wherein the unit cell is a cubic, face-centered cubic, body-centered cubic or hexagonal unit cell.

24. Device for the additive manufacturing of metallic components, prepared for carrying out the method according to one of the preceding claims.

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