PBF-LB/M of Low-Alloyed Steels: Bainite-like Microstructures despite High Cooling Rates

Language
en
Document Type
Article
Issue Date
2022-10-24
First published
2022-09-05
Issue Year
2022
Authors
Bartels, Dominic
Novotny, Tobias
Mohr, Andreas
Soest, Frank von
Hentschel, Oliver
Merklein, Carsten
Schmidt, Michael
Editor
Publisher
MDPI
Abstract

Laser-based powder bed fusion of metals (PBF-LB/M) is an emerging technology with enormous potential for the fabrication of highly complex products due to the layer-wise fabrication process. Low-alloyed steels have recently gained interest due to their wide potential range of applications. However, the correlation between the processing strategy and the material properties remains mostly unclear. The process-inherent high cooling rates support the assumption that a very fine martensitic microstructure is formed. Therefore, the microstructure formation was studied by means of scanning electron microscopy, hardness measurements, and an analysis of the tempering stability. It could be shown that additively manufactured Bainidur AM samples possess a bainitic microstructure despite the high process-specific cooling rates in PBF-LB/M. This bainitic microstructure is characterized by an excellent tempering stability up to temperatures as high as 600 °C. In contrast to this, additively manufactured and martensitic-hardened specimens are characterized by a higher initial hardness but a significantly reduced tempering stability. This shows the potential of manufacturing products from Bainidur AM for high-temperature applications without the necessity of a post-process heat treatment for achieving the desired bainitic microstructure.

Journal Title
Materials
Volume
15
Issue
17
Citation
Materials 15.17 (2022): 6171. <https://www.mdpi.com/1996-1944/15/17/6171>
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