19 results on '"Andreas Schiffl"'
Search Results
2. Analysis of Impact Factors on Crash Performance of High Strength 6082 Alloys Consider Extrudability and Small Modifications of the Profile Geometry
- Author
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Iris Schiffl, Andreas Schiffl, S. Brötz, Johannes A. Österreicher, Matthias Hartmann, and W. Kühlein
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010302 applied physics ,Materials science ,business.industry ,Work (physics) ,Automotive industry ,Geometry ,Crash ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,0103 physical sciences ,Leverage (statistics) ,0210 nano-technology ,business - Abstract
The ever-increasing requirements of the automotive industry in terms of crash performance necessitate the development of high strength modifications of the EN AW-6082 alloy. High amounts of strengthening elements such as Mg, Si, Cr, Mn, and Cu can lead to poor extrudability. The present work presents a statistical method for analysing the parameters to find the greatest degree of influencing leverage on extrudability. Additionally, some results from a second method reveal an improvement in crash performance of a given profile geometry. Small modifications of the rib junction of a two-chamber profile can lead to an improvement in crash performance
- Published
- 2019
3. A simplified machine learning product carbon footprint evaluation tool
- Author
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Silvio Lang, Bastian Engelmann, Andreas Schiffler, and Jan Schmitt
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Machine learning ,Product carbon footprint sustainability ,Environmental effects of industries and plants ,TD194-195 - Abstract
On the way to climate neutrality manufacturing companies need to assess the Carbon dioxide (CO2) emissions of their products as a basis for emission reduction measures. The evaluate this so-called Product Carbon Footprint (PCF) life cycle analysis as a comprehensive method is applicable, but means great effort and requires interdisciplinary knowledge. Nevertheless, assumptions must still be made to assess the entire supply chain. To lower these burdens and provide a digital tool to estimate the PCF with less input parameter and data, we make use of machine learning techniques and develop an editorial framework called MINDFUL. This contribution shows its realization by providing the software architecture, underlying CO2 factors, calculations and Machine Learning approach as well as the principles of its user experience. Our tool is validated within an industrial case study.
- Published
- 2024
- Full Text
- View/download PDF
4. Pixelwise high-temperature calibration for in-situ temperature measuring in powder bed fusion of metal with laser beam
- Author
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Dennis Höfflin, Christian Sauer, Andreas Schiffler, Jochen Manara, and Jürgen Hartmann
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Process monitoring ,High-temperature calibration ,PBF-LB/M ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
High-temperature calibration methods in additive manufacturing involve the use of advanced techniques to accurately measure and control the temperature of the build material during the additive manufacturing process. Infrared cameras, blackbody radiation sources and non-linear optimization algorithms are used to correlate the temperature of the material with its emitted thermal radiation. This is essential for ensuring the quality and repeatability of the final product. This paper presents the calibration procedure of an imaging system for in-situ measurement of absolute temperatures and temperature gradients during powder bed fusion of metal with laser beam (PBF-LB/M) in the temperature range of 500 K–1500 K. It describes the design of the optical setup to meet specific requirements in this application area as well as the procedure for accounting the various factors influencing the temperature measurement. These include camera-specific effects such as varying spectral sensitivities of the individual pixels of the sensor as well as influences of the exposure time and the exposed sensor area. Furthermore, influences caused by the complex optical path, such as inhomogeneous transmission properties of the galvanometer scanner as well as angle-dependent transmission properties of the f-theta lens were considered. A two-step fitting algorithm based on Planck's law of radiation was applied to best represent the correlation. With the presented procedure the calibrated thermography system provides the ability to measure absolute temperatures under real process conditions with high accuracy.
- Published
- 2024
- Full Text
- View/download PDF
5. Information depth in backscattered electron microscopy of nanoparticles within a solid matrix
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Gilles R. Bourret, Andreas Schiffl, Sabine Schwarz, Florian Grabner, and Johannes A. Österreicher
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010302 applied physics ,Materials science ,Number density ,Scanning electron microscope ,Mechanical Engineering ,Monte Carlo method ,Nanoparticle ,02 engineering and technology ,Electron ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Molecular physics ,Matrix (chemical analysis) ,Mechanics of Materials ,Transmission electron microscopy ,0103 physical sciences ,Microscopy ,General Materials Science ,0210 nano-technology - Abstract
Measuring the dimensions and number density of nanoparticles dispersed in a solid matrix is usually accomplished via transmission electron microscopy (TEM) which suffers from high cost, low throughput, and small analytical volume. In comparison, scanning backscattered electron microscopy is inexpensive, requires little sample preparation, and allows for the analysis of large sample areas. However, the information depth is usually not known precisely and depends on several factors such as the composition of the nanoparticles and the matrix as well as the size of the nanoparticles, hindering the reconstruction of the actual size distribution and three-dimensional number density. Here we present a method to estimate the information depth for spherical nanoparticles of different sizes in order to accurately determine size distribution and number density. The approach is based on Monte Carlo simulation of electron trajectories in the material and analysis of the obtained backscattered electron signal-to-noise-ratio. Our experimental results are compared to those obtained via TEM and good agreement is demonstrated; this shows that TEM can be replaced by scanning electron microscopy for studying nanocomposites in many cases.
- Published
- 2018
6. Verbesserte Crasheigenschaften hochfester Aluminium-Sicherheitsbauteile
- Author
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Di Johannes Österreicher, Di Simon Brötz, Matthias Hartmann, and Andreas Schiffl
- Subjects
Materials science - Published
- 2018
7. Improved crash characteristics of high-strength aluminum safety components
- Author
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Matthias Hartmann, Simon Brötz, Johannes A. Österreicher, and Andreas Schiffl
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010302 applied physics ,Materials science ,chemistry ,Aluminium ,0103 physical sciences ,chemistry.chemical_element ,Crash ,02 engineering and technology ,021001 nanoscience & nanotechnology ,0210 nano-technology ,01 natural sciences ,Automotive engineering - Published
- 2018
8. Secondary precipitation during homogenization of Al-Mg-Si alloys: Influence on high temperature flow stress
- Author
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Johannes A. Österreicher, Andreas Schiffl, Gilles R. Bourret, Manoj Kumar, and Sabine Schwarz
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Materials science ,Precipitation (chemistry) ,020502 materials ,Mechanical Engineering ,Metallurgy ,02 engineering and technology ,Flow stress ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,Homogenization (chemistry) ,0205 materials engineering ,Mechanics of Materials ,visual_art ,Aluminium alloy ,visual_art.visual_art_medium ,Formability ,General Materials Science ,Extrusion ,Dilatometer ,0210 nano-technology - Abstract
In the automotive industry Al-Mg-Si alloys are often chosen for high strength extruded profiles. However, the production of such profiles can be challenging for high alloy contents. Among several processing steps, the homogenization heat treatment before extrusion is readily accessible to modifications to improve high temperature formability. In this work, the influence of five different homogenization variants on the flow stress of AA6082 at elevated temperatures was assessed by compression testing in a deformation dilatometer at 450 °C, 480 °C, and 510 °C. The observed differences in flow stress were interpreted with regards to the microstructure. Samples from billets homogenized at higher soak temperatures exhibited lower hot flow stresses in subsequent dilatometer testing, indicating better processability. Since the decrease in flow stress is approximately constant at all test temperatures, it is suggested that it is due to a lower number density of relatively temperature-stable α-Al(Mn,Fe)Si dispersoids formed during homogenization at higher temperatures; these dispersoids are stable at all three test temperatures. In contrast, the influence of a cooling rate variation was relatively minor and diminishes at higher test temperatures since Mg-Si precipitates – whose size and number density is affected by changes of the cooling rate – are less stable at the higher test temperatures.
- Published
- 2017
9. Sample preparation methods for scanning electron microscopy of homogenized Al-Mg-Si billets: A comparative study
- Author
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Gilles R. Bourret, Andreas Schiffl, Sabine Schwarz, Daniel Hillebrand, Johannes A. Österreicher, and Manoj Kumar
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010302 applied physics ,Materials science ,Scanning electron microscope ,Mechanical Engineering ,Alloy ,Analytical chemistry ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Electropolishing ,Mechanics of Materials ,visual_art ,0103 physical sciences ,Aluminium alloy ,visual_art.visual_art_medium ,engineering ,General Materials Science ,Sample preparation ,0210 nano-technology ,High-resolution transmission electron microscopy ,Dissolution - Abstract
Characterization of Mg-Si precipitates is crucial for optimizing the homogenization heat treatment of Al-Mg-Si alloys. Although sample preparation is key for high quality scanning electron microscopy imaging, most common methods lead to dealloying of Mg-Si precipitates. In this article we systematically evaluate different sample preparation methods: mechanical polishing, etching with various reagents, and electropolishing using different electrolytes. We demonstrate that the use of a nitric acid and methanol electrolyte for electropolishing a homogenized Al-Mg-Si alloy prevents the dissolution of Mg-Si precipitates, resulting in micrographs of higher quality. This preparation method is investigated in depth and the obtained scanning electron microscopy images are compared with transmission electron micrographs: the shape and size of Mg-Si precipitates appear very similar in either method. The scanning electron micrographs allow proper identification and measurement of the Mg-Si phases including needles with lengths of roughly 200 nm. These needles are β″ precipitates as confirmed by high resolution transmission electron microscopy.
- Published
- 2016
10. Herausforderungen bei der Präparation von metallischen Hybridwerkstoffen
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Christa Kainhofer, K. J.M. Papis, Werner Fragner, and Andreas Schiffl
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Mechanics of Materials ,Metals and Alloys ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Abstract
Kurzfassung Die Präparation von monolitischen metallischen Werkstoffen für die spätere metallografische Bewertung ist gängige Praxis. Die Schliffherstellung von Werkstoffhybriden ist allerdings schwieriger. Gründe hierfür sind unterschiedliches Werkstoffverhalten hinsichtlich mechanischer Beanspruchung (Abrasion beim Schleifen und Polieren) sowie chemisches Verhalten bei anschließenden Ätzungen. Werkstoffverbunde werden allerdings immer öfter sowohl im wissenschaftlichen als auch im industriellen Umfeld nachgefragt und eingesetzt. Um die Qualität dieser Werkstoffverbunde, insbesondere die der Fügestelle, zu prüfen und zu charakterisieren werden diese Verbunde metallografisch untersucht. Daher ist eine Adaption der metallografischen Verfahren an das jeweilige System notwendig. Dieser Artikel beschäftigt sich mit der Charakterisierung des Systems Aluminium-Eisen und der etwaigen auftretenden intermetallischen Phasen, auch im Mehrkomponentensystem bei Legierungen. Die dabei auftretenden Herausforderungen werden dargestellt und anschließend eine Verfahrensroute zur Erstellung hochqualitativer Ergebnisse für die Beurteilung des Verbunds vom Schliff bis zur rasterelektronischen Aufnahme aufgezeigt.
- Published
- 2009
11. Einfluss von SiC-Partikeln und Gießgeschwindigkeit auf die Korngröße einer im Strangguss vergossenen Magnesiumlegierung HP AZ31
- Author
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Mark Alan Easton and Andreas Schiffl
- Subjects
Gynecology ,Physics ,medicine.medical_specialty ,medicine ,General Medicine ,General Chemistry - Abstract
SiC-Partikel sind effektive Kornfeiner fur Mg-Al-Legierungen. In Legierungen mit geringen Aluminiumkonzentrationen ist die starkste Reduktion in der Korngrose zu beobachten, wenn ein effektiver Kornfeiner zugegeben wird. Aus diesem Grund wurden die Versuche mit einer kommerziellen HP AZ31 durchgefuhrt. Durch die Zugabe von SiC-Partikeln steigt der Gehalt an Mg2Si-Phasen an, und unter Einbezug von Phasengleichgewichten kann angenommen werden, dass sich die SiC-Partikel in Al4C3-Partikel umwandeln. Diese stehen der Kornfeinung von Mg-Al-Legierungen als aktiver Keim zur Verfugung, denn die Gitterfehlpassung zwischen Al4C3, SiC und Magnesium liegt fur alle im Bereich von ca. 4 %. Die in den Laborgiesversuchen erzielten guten, reproduzierbaren Kornfeinungsergebnisse bei Verwendung von SiC als Kornfeiner wurden an einer industriellen Vertikalstranggiesanlage verifiziert. Der Einfluss der Giesgeschwindigkeit und des Einsatzes von SiC zur Kornfeinung wurde uber den Querschnitt des Stranggussbolzens untersucht. Eine hohere Giesgeschwindigkeit verringert die Korngrose am Rand des Bolzens von nicht korngefeinten Legierungen, verschlechtert aber den Korngrosenverlauf uber den Querschnitt. Dieser inhomogene Verlauf ist nicht akzeptabel. Nach der Zugabe von SiC-Partikeln stellt sich ein homogener Korngrosenverlauf uber den Querschnitt ein, unabhangig von der Giesgeschwindigkeit.
- Published
- 2009
12. Influence of SiC Particles on the Grain Refinement of an Mg-Al Alloy
- Author
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Mark Alan Easton and Andreas Schiffl
- Subjects
Materials science ,Mechanical Engineering ,Metallurgy ,Alloy ,engineering.material ,Condensed Matter Physics ,Microstructure ,Grain size ,Carbide ,Mechanics of Materials ,Phase (matter) ,engineering ,Particle ,General Materials Science ,Grain boundary ,Ternary operation - Abstract
SiC particles are effective grain refiners in Mg-Al alloys. Several investigations, from different researchers, into their effect on a range of alloys with different Al contents has been undertaken and it has been found that the greatest reduction in grain size occurs in alloys having low Al contents. Performing grain refinement studies on a range of alloy contents also allows for further investigation into the mechanisms of grain refinement. It was found that the size of the SiC particles is also important in magnesium grain refinement. However, the presence of Mg2Si in the microstructure and the consideration of phase equilibria suggest that SiC can transform into other binary or ternary carbides. If such carbides are formed, they may also act as an effective grain refiner for Mg-Al alloys. In this study, the possibility of formation of new carbides (Al4C3, Al2MgC2, Mn7C3, Mg2C, Mg2C3, Al2CO etc.) and their ability to be good grain refiners for Mg-Al alloys is discussed.
- Published
- 2009
13. Metallographie luftexponierter Aluminium-Kohlenstofffaser-Verbundwerkstoffe mit Grenzflächenkarbiden
- Author
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Peter Schulz, Andreas Schiffl, and Christa Kainhofer
- Subjects
Materials science ,Mechanics of Materials ,visual_art ,Metals and Alloys ,Carbon fibers ,visual_art.visual_art_medium ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Nuclear chemistry - Abstract
Kurzfassung Kohlenstofffaser-Aluminiummatrix-Verbundwerkstoffe sind attraktive Kandidaten für Bauteile, die einen kleinen thermischen Ausdehnungskoeffizienten bei gleichzeitig hoher Wärmeleitfähigkeit aufweisen müssen. Die Herstellung von Aluminium-Kohlenstoff-Verbund-werkstoffen erfolgt durch Gasdruckinfiltration in einem Autoklav. Die wichtigsten Herstellungsparameter sind die Schmelzetemperatur und die Zeit, in der die Fasern mit der Aluminiumschmelze in Berührung stehen. Wenn eine Reaktion von flüssigem Aluminium mit den Kohlefasern auftritt, können Aluminiumkarbide gebildet werden, diese schwächen den Verbund enorm. Die Schwierigkeit in der Präparation dieser kleinen Karbide liegt darin, dass diese wasserlöslich sind und nur im Faser/Matrix-Interfacebereich zu finden sind. Es muss daher besonders auf Wasserfreiheit geachtet werden. Die Metallographie ist ein entscheidender Baustein zur Beurteilung der Qualität von Kohlenstofffaser verstärkten Aluminiummatrix-Verbundwerkstoffen. Sie ist leicht anzuwenden und lässt Rückschlüsse auf die Verbundeigenschaften zu. Mit Hilfe der Metallographie lassen sich Herstellungsparameter eingrenzen und geeignete Fasersorten selektieren.
- Published
- 2008
14. Grain refinement of Mg–Al(–Mn) alloys by SiC additions
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Andreas Schiffl, Ji Yong Yao, H. Kaufmann, and Mark Alan Easton
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Materials science ,Magnesium ,Mechanical Engineering ,Metallurgy ,Metals and Alloys ,chemistry.chemical_element ,Condensed Matter Physics ,Microstructure ,Casting ,Grain size ,chemistry ,Mechanics of Materials ,Phase (matter) ,General Materials Science ,Solidification microstructure ,Refining (metallurgy) - Abstract
The addition of SiC particles effectively grain refined a range of Mg-Al alloys. The greatest reductions in grain size were found for the alloys with lower Al contents. The presence of Mg2Si in the microstructure after that SiC addition, and consideration of phase equilibria suggested that the SiC transforms to Al4C3, and this is the actual nucleant. The addition of Mn poisoned the grain refining effect of the SiC addition, probably due to the formation of less potent Al-Mn-carbides. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
- Published
- 2006
15. Powder Bed Monitoring Using Semantic Image Segmentation to Detect Failures during 3D Metal Printing
- Author
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Anna-Maria Schmitt, Christian Sauer, Dennis Höfflin, and Andreas Schiffler
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additive manufacturing ,metal printing ,neural network ,semantic segmentation ,thermal distortion ,in situ monitoring ,Chemical technology ,TP1-1185 - Abstract
Monitoring the metal Additive Manufacturing (AM) process is an important task within the scope of quality assurance. This article presents a method to gain insights into process quality by comparing the actual and target layers. Images of the powder bed were captured and segmented using an Xception–style neural network to predict the powder and part areas. The segmentation result of every layer is compared to the reference layer regarding the area, centroids, and normalized area difference of each part. To evaluate the method, a print job with three parts was chosen where one of them broke off and another one had thermal deformations. The calculated metrics are useful for detecting if a part is damaged or for identifying thermal distortions. The method introduced by this work can be used to monitor the metal AM process for quality assurance. Due to the limited camera resolutions and inconsistent lighting conditions, the approach has some limitations, which are discussed at the end.
- Published
- 2023
- Full Text
- View/download PDF
16. Microstructure and mechanical properties of high strength Al—Mg—Si—Cu profiles for safety parts
- Author
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Georg Falkinger, Johannes A. Österreicher, Gilles R. Bourret, and Andreas Schiffl
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010302 applied physics ,Coalescence (physics) ,education.field_of_study ,Materials science ,Population ,Intermetallic ,chemistry.chemical_element ,02 engineering and technology ,Die swell ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,chemistry ,Aluminium ,0103 physical sciences ,Forensic engineering ,Composite material ,Elongation ,0210 nano-technology ,education ,Tensile testing - Abstract
Aluminium extrudate used for safety parts in cars need to exhibit high yield strength and ductility, a combination that is not easily achieved. In this work, the mechanical properties and microstructure of profiles with a yield strength greater than 280MPa achieved by two different artificial ageing treatments were studied. Profiles from one of the heat treatments performed well in quasi-static compression testing while those from the other heat treatment clearly failed. The batch of profiles that failed showed higher uniform elongation in tensile testing but a lower reduction in area. However, the difference in bending angles in the three-point-bending test were not as pronounced. Microscopic investigation of polished sections and fracture surfaces revealed that failure is dominated by the fracture of intermetallic phases resulting in voids. The growth and coalescence of these voids is facilitated by another population of smaller voids within the matrix, presumably nucleating at secondary phases.
- Published
- 2016
17. GrenzfläChenreaktionen Bei Der Herstellung Von SiCP-Magnesium Oder -Aluminium Metallmatrix- Verbundwerkstoffen auf schmelzmetallurgischem Weg
- Author
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Andreas Schiffl
- Published
- 2009
18. Process Monitoring Using Synchronized Path Infrared Thermography in PBF-LB/M
- Author
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Dennis Höfflin, Christian Sauer, Andreas Schiffler, and Jürgen Hartmann
- Subjects
SPIT ,PBF-LB/M ,additive manufacturing ,process monitoring ,SWIR ,melt pool ,Chemical technology ,TP1-1185 - Abstract
Additive manufacturing processes, particularly Laser-Based Powder Bed Fusion of Metals (PBF-LB/M), enable the development of new application possibilities due to their manufacturing-specific freedom of design. These new fields of application require a high degree of component quality, especially in safety-relevant areas. This is currently ensured primarily via a considerable amount of downstream quality control. Suitable process monitoring systems promise to reduce this effort drastically. This paper introduces a novel monitoring method in order to gain process-specific thermal information during the manufacturing process. The Synchronized Path Infrared Thermography (SPIT) method is based on two synchronized galvanometer scanners allowing high-speed and high-resolution observations of the melt pool in the SWIR range. One scanner is used to steer the laser over the building platform, while the second scanner guides the field of view of an IR camera. With this setup, the melting process is observed at different laser powers, scan speeds and at different locations with respect to the laser position, in order to demonstrate the positioning accuracy of the system and to initially gain thermal process data of the melt pool and the heat-affected zone. Therefore, the SPIT system shows a speed independent overall accuracy of ±2 Pixel within the evaluated range. The system further allows detailed thermal observation of the melt pool and the surrounding heat-affected zone.
- Published
- 2022
- Full Text
- View/download PDF
19. Opto-Thermal Investigation of Additively Manufactured Steel Samples as a Function of the Hatch Distance
- Author
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Dennis Höfflin, Maximilian Rosilius, Philipp Seitz, Andreas Schiffler, and Jürgen Hartmann
- Subjects
DMLS ,additive manufacturing ,laser flash method ,thermal diffusivity ,Chemical technology ,TP1-1185 - Abstract
Nowadays, additive manufacturing processes are becoming more and more appealing due to their production-oriented design guidelines, especially with regard to topology optimisation and minimal downstream production depth in contrast to conventional technologies. However, a scientific path in the areas of quality assurance, material and microstructural properties, intrinsic thermal permeability and dependent stress parameters inhibits enthusiasm for the potential degrees of freedom of the direct metal laser melting process (DMLS). Especially in quality assurance, post-processing destructive measuring methods are still predominantly necessary in order to evaluate the components adequately. The overall objective of these investigations is to gain process knowledge make reliable in situ statements about component quality and material properties based on the process parameters used and emission values measured. The knowledge will then be used to develop non-destructive tools for the quality management of additively manufactured components. To assess the effectiveness of the research design in relation to the objectives for further investigations, this pre-study evaluates the dependencies between the process parameters, process emission during manufacturing and resulting thermal diffusivity and the relative density of samples fabricated by DMLS. Therefore, the approach deals with additively built metal samples made on an EOS M290 apparatus with varying hatch distances while simultaneously detecting the process emission. Afterwards, the relative density of the samples is determined optically, and thermal diffusivity is measured using the laser flash method. As a result of this pre-study, all interactions of the within factors are presented. The process variable hatch distance indicates a strong influence on the resulting material properties, as an increase in the hatch distance from 0.11 mm to 1 mm leads to a drop in relative density of 57.4%. The associated thermal diffusivity also reveals a sharp decrease from 5.3 mm2/s to 1.3 mm2/s with growing hatch distances. The variability of the material properties can also be observed in the measured process emissions. However, as various factors overlap in the thermal radiation signal, no clear assignment is possible within the scope of this work.
- Published
- 2021
- Full Text
- View/download PDF
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