Method for manufacturing a metallic component and component

Abstract

The invention relates to a method for manufacturing a metallic component, wherein a granular starting material with a plurality of grains is provided and a laser beam is applied to it. The starting material comprises at least the components carbon, chromium, silicon, manganese, and iron. The invention further relates to a metallic component manufactured in this manner.

Description

[0001] The invention relates to a method for manufacturing a metallic component and to a component manufactured by means of such a method.

[0002] Metallic components are used for a variety of purposes, for example in motor vehicles. Especially during the development and testing phase of complex products like vehicles, it is often desirable to be able to manufacture a metallic component quickly without having to create elaborate molds or similar structures beforehand. Additive manufacturing processes such as 3D printing are used for this purpose. However, it has become apparent, particularly with metallic components, that known designs can only achieve material properties that often do not correspond to those required in the final product.

[0003] The invention is therefore based on the objective of manufacturing metallic components in such a way that a wide variety of properties can be achieved with minimal effort when these components are produced using an additive manufacturing process. According to the invention, this is achieved by a method and a component as defined in the respective main claims. Advantageous embodiments can be found, for example, in the respective dependent claims. The content of the claims is incorporated into the description by express reference.

[0004] The invention relates to a method for manufacturing a metallic component. The method comprises the following steps: - Providing a granular starting material, comprising a variety of grains, and - Applying a laser beam to the starting material so that some of the grains are selectively melted and combine to form the component.

[0005] The starting material is preferably composed of at least the following components: - Carbon, - Chrome, - Silicon, - Manganese, - Iron.

[0006] Using such a starting material, it is possible to achieve very different properties of a manufactured metallic component by varying the subsequent process. In principle, the same starting material or the same chemical composition can be used. Therefore, the need to keep different starting materials on hand can be advantageously avoided. The following sections describe process parameters that make it possible to adjust different material properties. Furthermore, additional specifications for the composition of the starting material, which have proven particularly advantageous for the purpose described here, are also provided.

[0007] Preferably, the carbon content is at least 0.01% and / or at most 0.03%. Preferably, the chromium content is at least 10.5% and / or at most 11.75%. Preferably, the silicon content is at least 0.1% and / or at most 1%. Preferably, the manganese content is at least 0.1% and / or at most 1%. Preferably, the starting material also contains phosphorus at most 0.04%. Preferably, the starting material contains only the specified components. This means, in particular, that no other metals or other components are actively added. Unavoidable impurities that are not intentionally added are disregarded in this consideration. In particular, it can therefore be provided that the starting material consists only of carbon, chromium, silicon, manganese, and iron, or that it consists of carbon, chromium, silicon, manganese, phosphorus, and iron.

[0008] The percentages mentioned herein refer in particular to weight percentages.

[0009] In particular, the starting material can have a grain size of at least 15 µm and / or at most 53 µm.

[0010] According to one embodiment, the laser beam has a power output of at least 295 W and / or at most 299 W. In particular, it can have a power output of 297 W.

[0011] According to one embodiment, the laser beam has a power output of at least 335 W and / or at most 345 W. In particular, it can have a power output of 340 W.

[0012] According to one embodiment, the laser beam is moved across the starting material at a speed of at least 950 mm / s and / or at most 1,050 mm / s. In particular, it can be moved across the starting material at a speed of 1,000 mm / s.

[0013] According to one embodiment, the laser beam is moved across the starting material at a speed of at least 750 mm / s and / or at most 850 mm / s. In particular, it can be moved across the starting material at a speed of 800 mm / s.

[0014] Moving the laser beam across the starting material at a specific speed refers to the speed at which a point where the laser beam strikes the starting material, for example, its center, moves along a particularly imaginary surface. This surface can, for example, be designed in such a way that it covers surface roughness caused by the graininess of the starting material and forms a flat or at least uniform or non-rough imaginary surface.

[0015] According to one embodiment, the laser beam is moved across the starting material with a track spacing of at least 0.12 mm and / or at most 0.13 mm. In particular, it can be moved across the starting material with a track spacing of 0.125 mm. According to another embodiment, the laser beam is moved across the starting material with a track spacing of at least 0.105 mm and / or at most 0.115 mm. In particular, it can be moved across the starting material with a track spacing of 0.11 mm.

[0016] A track spacing refers specifically to the distance between two immediately adjacent tracks along which the laser beam moves across the target material. The track spacing can be defined, for example, by the center points of the laser beam.

[0017] In particular, the laser beam can be used to melt the starting material to a layer thickness of at least 0.05 mm and / or at most 0.07 mm, preferably 0.06 mm. This can mean, in particular, that starting from a surface, for example, a hypothetical surface as mentioned above or a real, physically existing surface, the starting material is melted to a specified depth. This typically fuses adjacent grains of the starting material together, thus forming the component.

[0018] After a layer has been formed, further starting material can be applied to the already manufactured part of the component so that the next layer can be formed.

[0019] According to an advantageous embodiment, the component is heat-treated after the laser beam has been applied. This allows for further hardening of the component, particularly in a shape determined by the laser beam application. Specifically, the component can be heat-treated for a period of at least four hours and / or at most six hours, or for five hours. Such durations have proven advantageous for typical designs. However, other durations can also be used in principle. Heat treatment can also be omitted.

[0020] According to one embodiment, the component is heat-treated at a temperature of at least 725 °C and / or at most 775 °C, particularly 750 °C. According to another embodiment, the component is heat-treated at a temperature of at least 675 °C and / or at most 725 °C, particularly 700 °C. According to another embodiment, the component is heat-treated at a temperature of at least 850 °C and / or at most 900 °C, or at 875 °C. According to yet another embodiment, the component is heat-treated at a temperature of at least 975 °C and / or at most 1,025 °C, or at 1,000 °C. Such temperature ranges have proven advantageous, particularly for achieving typical desired properties. By selecting different temperature ranges, certain properties of the component, especially with regard to the material that forms, can be deliberately controlled.

[0021] In particular, the component can be cleaned of surrounding particles after the laser beam has been applied. This leaves the component ready for immediate use. For example, the particles can be blown or washed off.

[0022] The invention further relates to a component which was manufactured using a method described herein. With regard to the method, all embodiments and variants described herein may be used.

[0023] In particular, additive manufacturing, on which the process described herein is based, allows components to be built up layer by layer. Component volume can be created within a free build space. For example, in a powder bed-based process such as Selective Laser Melting (SLM), metal powder is melted, specifically to form a solidified component. Each layer of the component is defined beforehand using parameterized vector paths. This layer-by-layer melting occurs at layer thicknesses of just a few hundredths of a millimeter, typically thousands of times per component. The finished component is then cleaned of the unmelted powder. This unmelted powder can be reused in the next build process.

[0024] The components produced in this way can, for example, be prototypes for development phases in the automotive industry. However, it has been shown that additive manufacturing processes known from the prior art are typically unable to replicate the material properties, for example with regard to strength and elongation at break, of components as they are mass-produced, especially in such a way that this is done with minimal effort.

[0025] Unlike conventional manufacturing processes such as casting or machining, additive manufacturing offers fast and tool-free production of components, resulting in significant time and cost advantages during the development process. However, alloys known from the state of the art for selective laser melting are generally atypical for use in the automotive industry.

[0026] The explanations described herein are based in particular on development work aimed at providing a starting material with a specific chemical composition, enabling the simple replication of various material properties, such as those typically found in mass-produced products. This replication is specifically designed to allow for the targeted achievement of different material properties through the selection of parameters in the additive manufacturing process. The starting material can be in powder form. It can be produced, in particular, through an atomization process with particle sizes between 15 µm and 53 µm.

[0027] The chemical composition of the starting material can be such that it meets the minimum and maximum values ​​specified below: Chemical composition C (carbon) Cr(Chromium) Si (Silicon) Mn(Manganese) P(Phosphorus) Fe(Iron) Min in % 0,01 10,5 0,1 0,1 0 rest Max in % 0,03 11,75 1 1 0,04 rest

[0028] As is the case elsewhere here, the percentages are given in weight percent.

[0029] To vary the material properties, laser power P, laser velocity v, laser track spacing h, and layer thickness I are key process parameters. The laser power P is typically the power emitted by the laser source. The laser velocity v typically describes the speed at which the laser spot moves across the powder plane along its path. The laser track spacing h describes the distance between adjacent laser track paths. The layer thickness I describes the thickness of the applied individual layers of powder.

[0030] The volume energy E introduced into the powder can be calculated using these four parameters: E=P / (v*h*l).

[0031] This is how the energy of the melt pool can be described. For example, more energy can be introduced into the powder with a higher laser power P. Similarly, more energy is introduced with a slower speed v. However, less energy is introduced with a larger spacing h between the paths or larger layers I. In an optimal printing process, the grains can be completely melted, but typically not too deeply into the preceding layer. Otherwise, no volume would be built up; instead, the material would be welded inwards. The technically usable and advantageous parameter combinations were identified in experiments. The resulting parameter field leads to different material properties. Subsequent heat treatment of the printed component at different temperatures C produces further variations in material properties.

[0032] In particular, the following combinations of key performance indicators were targeted: Mechanical properties Key value combination Yield strength Rp0.2 [MPa] Tensile strength Rm [MPa] Elongation at break A [%] Modulus of elasticity E [MPa] HRC hardness 1 335 ± 20 500 ± 35 14 ± 3 190 ± 30 20 ± 5 HRC 2 830 ± 50 1020 ± 100 14±3 190 ± 30 30 ± 5 HRC 3 460 ± 35 620 ± 50 23 ± 4 220 ± 30 20 ± 5 HRC 4 400 ± 20: 575 ± 35 27 ± 5 220 ± 30 20 ± 5 HRC 5 355 ± 20 550 ± 35 28 ± 5 220 ± 30 20 ± 5 HRC 6 310 ± 20 535 ± 35 30 ± 5 220 ± 30 20 ± 5 HRC

[0033] It has been shown that the following parameters or parameter combinations are particularly well suited to achieving the combinations: Pressure parameters Heat treatment Key value combination Laser power P [W] Laser velocity v [mm / s] Track spacing h [mm] Layer thickness I [mm] Temperature T [°C] Lasts [h] 1 297 1000 0,125 0,06 750 5 2 340 800 0,11 0,06 - - 3 340 800 0,11 0,06 700 5 4 340 800 0,11 0,06 750 5 5 340 800 0,11 0,06 875 5 6 340 800 0,11 0,06 1000 5

[0034] If only a dash is entered for heat treatment, this means that no heat treatment is carried out.

[0035] Typically, some deviation from the specified parameters is possible. It's also possible to select only one parameter or only some of the specified parameters as indicated, in which case the desired properties may not be fully achieved, but at least partially.

[0036] Manufacturing typically takes place in a cold build chamber, which can mean, in particular, that a powder temperature of 200 °C is not exceeded.

[0037] Further features and advantages will be evident to those skilled in the art from the following description of an exemplary embodiment, which refers to the accompanying drawing. This shows: Fig. 1: a device for carrying out a method described herein.

[0038] Fig.Figure 1 schematically shows a device 10 by means of which a method described herein can be carried out and, in particular, a metallic component 15 can be manufactured. The device 10 has a receptacle 20, which is designed as an upwardly open receiving chamber. The device 10 also has a laser 30, which emits a laser beam 35. The laser 30 is pivotable by means not shown, so that the laser beam 35 can be directed to a specific location within the receptacle 20. In particular, specific two-dimensional patterns can be traced on an imaginary or real surface within the receptacle 20.

[0039] In the image 20, there is a starting material 22, which is present in the form of a multitude of grains 24. The grains 24 all have the same chemical composition. Regarding possible compositions, reference is made to the description already given above. When the laser 30 is activated so that it emits a laser beam 35, this laser beam 35 strikes the starting material 22 and melts it. This creates the component 15, which is built up layer by layer from bottom to top. After a layer in the form of a horizontal two-dimensional layer has been created by the laser beam 35, i.e., after grains 24 have been melted at all the necessary points so that they fuse together upon cooling, further starting material 22 is applied to the component 15 after the completion of the build-up of such a layer, so that the next layer can be created.This process continues until component 15 is completely finished. This allows for the creation of virtually any three-dimensional structure for component 15. By varying the laser parameters and the parameters used in the production of component 15, different material properties, such as strength and yield strength, can be achieved without altering the chemistry of the starting material 22.

[0040] The steps of the method according to the invention can be carried out in the specified order. However, they can also be carried out in a different order, provided this is technically feasible. The method according to the invention can be carried out in one embodiment, for example with a specific combination of steps, in such a way that no further steps are performed. However, further steps can also be carried out in principle, including those not mentioned.

[0041] It should be noted that features may be described in combination in the claims and description, for example to facilitate understanding, even though they can also be used separately. The person skilled in the art recognizes that such features can also be combined independently with other features or combinations of features.

[0042] References in dependent claims may indicate preferred combinations of the respective features, but do not exclude other combinations of features. Reference symbol list 10 Device 15 components 20 recordings 22 Source material 24 grains 30 lasers 35 Laser beam

Claims

Method for producing a metallic component (15), wherein the method comprises the following steps: - providing a granular starting material (22) comprising a plurality of grains (24), and - applying a laser beam to the starting material (22) such that some of the grains are selectively melted and combine to form the component (15), wherein the starting material (22) is composed of at least the following components: - carbon, - chromium, - silicon, - manganese, - iron. The method according to claim 1, wherein the proportion of carbon is at least 0.01% and / or at most 0.03%. Method according to one of the preceding claims, wherein the proportion of chromium is at least 10.5% and / or at most 11.75%. Method according to one of the preceding claims, wherein the silicon content is at least 0.1% and / or at most 1%. Method according to one of the preceding claims, wherein the proportion of manganese is at least 0.1% and / or at most 1%. Method according to one of the preceding claims, wherein the starting material (22) further comprises phosphorus in a proportion of at most 0.04%. Method according to one of the preceding claims, wherein the starting material (22) comprises exclusively the specified components. Method according to one of the preceding claims, wherein the starting material (22) has a grain size of at least 15 mm and / or at most 53 mm. Method according to any of the preceding claims, wherein the laser beam has a power of at least 295 W and / or at most 299 W, or of 297 W, or wherein the laser beam has a power of at least 335 W and / or at most 345 W, or of 340 W. Method according to one of the preceding claims,- wherein the laser beam is moved over the starting material (22) at a speed of at least 950 mm / s and / or at most 1,050 mm / s, or 1,000 mm / s, or- wherein the laser beam is moved over the starting material (22) at a speed of at least 750 mm / s and / or at most 850 mm / s, or 800 mm / s. Method according to one of the preceding claims,- wherein the laser beam is moved over the starting material (22) with a track spacing of at least 0.12 mm and / or at most 0.13 mm, or of 0.125 mm, or- wherein the laser beam is moved over the starting material (22) with a track spacing of at least 0.105 mm and / or at most 0.115 mm, or of 0.11 mm. Method according to one of the preceding claims, wherein the starting material (22) is melted to a layer thickness of at least 0.05 mm and / or at most 0.07 mm, or 0.06 mm. Method according to one of the preceding claims, wherein the component (15) is heat-treated after the application of the laser beam. Method according to claim 13, wherein the component (15) is heat-treated for a period of at least 4 h and / or at most 6 h, or 5 h. Method according to one of claims 13 or 14, wherein the component (15) is heat-treated at a temperature of at least 725 °C and / or at most 775 °C, or at 750 °C, or wherein the component (15) is heat-treated at a temperature of at least 675 °C and / or at most 725 °C, or at 700 °C, or wherein the component (15) is heat-treated at a temperature of at least 850 °C and / or at most 900 °C, or at 875 °C, or wherein the component (15) is heat-treated at a temperature of at least 975 °C and / or at most 1,025 °C, or at 1,000 °C. Method according to one of the preceding claims, wherein the component (15) is cleaned of surrounding grains (24) after the application of the laser beam. Component (15) which was manufactured by a method according to one of the preceding claims.

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