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Main Title: Experimental Determination of the Emissivity of Powder Layers and Bulk Material in Laser Powder Bed Fusion Using Infrared Thermography and Thermocouples
Author(s): Mohr, Gunther
Nowakowski, Susanna
Altenburg, Simon J.
Maierhofer, Christiane
Hilgenberg, Kai
Type: Article
Abstract: Recording the temperature distribution of the layer under construction during laser powder bed fusion (L-PBF) is of utmost interest for a deep process understanding as well as for quality assurance and in situ monitoring means. While having a notable number of thermal monitoring approaches in additive manufacturing (AM), attempts at temperature calibration and emissivity determination are relatively rare. This study aims for the experimental temperature adjustment of an off-axis infrared (IR) thermography setup used for in situ thermal data acquisition in L-PBF processes. The temperature adjustment was conducted by means of the so-called contact method using thermocouples at two different surface conditions and two different materials: AISI 316L L-PBF bulk surface, AISI 316L powder surface, and IN718 powder surface. The apparent emissivity values for the particular setup were determined. For the first time, also corrected, closer to real emissivity values of the bulk or powder surface condition are published. In the temperature region from approximately 150 °C to 580 °C, the corrected emissivity was determined in a range from 0.2 to 0.25 for a 316L L-PBF bulk surface, in a range from 0.37 to 0.45 for 316L powder layer, and in a range from 0.37 to 0.4 for IN718 powder layer.
Subject(s): laser powder bed fusion
selective laser melting
laser beam melting
process monitoring
Issue Date: 20-Nov-2020
Date Available: 29-Dec-2020
Language Code: en
DDC Class: 600 Technik, Technologie
Journal Title: Metals
Publisher: MDPI
Volume: 10
Issue: 11
Article Number: 1546
Publisher DOI: 10.3390/met10111546
EISSN: 2075-4701
TU Affiliation(s): Fak. 5 Verkehrs- und Maschinensysteme » Inst. Werkzeugmaschinen und Fabrikbetrieb » FG Verfahren und Technologien für hochbeanspruchte Schweißverbindungen
Appears in Collections:Technische Universität Berlin » Publications

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