Advanced process control in laser-based powder bed fusion–Smart Fusion feedback-loop control as a path to uniform properties for complex structures?

Laser-based powder bed fusion of metals (PBF-LB/M) enables the production of complex parts with high freedom of design. However, changes in cross-sectional area with build height influence inter-layer times and heat dissipation, resulting in potential local overheating. Since the temperature affects...

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Main Authors: Florian Nahr, Tobias Novotny, Dominik Kunz, Ulrich Kleinhans, Lova Chechik, Dominic Bartels, Michael Schmidt
Format: Article
Language:English
Published: Elsevier 2025-01-01
Series:Journal of Materials Research and Technology
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Online Access:http://www.sciencedirect.com/science/article/pii/S2238785424028175
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author Florian Nahr
Tobias Novotny
Dominik Kunz
Ulrich Kleinhans
Lova Chechik
Dominic Bartels
Michael Schmidt
author_facet Florian Nahr
Tobias Novotny
Dominik Kunz
Ulrich Kleinhans
Lova Chechik
Dominic Bartels
Michael Schmidt
author_sort Florian Nahr
collection DOAJ
description Laser-based powder bed fusion of metals (PBF-LB/M) enables the production of complex parts with high freedom of design. However, changes in cross-sectional area with build height influence inter-layer times and heat dissipation, resulting in potential local overheating. Since the temperature affects the microstructure and material properties, controlling the thermal history is necessary. To achieve this, a dynamic adjustment of energy input in response to the thermal conditions is required. Smart Fusion feedback-loop control monitors gray values recorded by optical tomography and compares them to a material and process specific target. If any deviations are identified, the system corrects them by applying locally varied laser power in the next layer. This study investigates the impact of the feedback-loop control on the microstructure evolution of titanium alloy Ti6Al4V and maraging steel MS1. Cuboids and complex parts with heat-accumulating features were manufactured using feedback-loop control and directly compared to their open-loop counterparts. Gray value profiles of the open-loop complex parts revealed large variations in temperature and geometry dependent differences in microstructure. The Smart Fusion feedback-loop control lead to a more constant temperature profile. In Ti6Al4V, this made the microstructure go from tempered martensite in the bulk section of the open-loop part to a consistent acicular martensitic structure in the feedback-loop controlled part. In MS1, the open-loop lead to signs of in-situ precipitation resulting in a significant local hardness increase in comparison to the feedback-loop control. Finally, the complex MS1 part could be built without minimum exposure times and uniform hardness of 350 HV0.5.
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spelling doaj-art-964e46ad7b8b4c73856129da6f7f08412025-01-19T06:25:07ZengElsevierJournal of Materials Research and Technology2238-78542025-01-0134604618Advanced process control in laser-based powder bed fusion–Smart Fusion feedback-loop control as a path to uniform properties for complex structures?Florian Nahr0Tobias Novotny1Dominik Kunz2Ulrich Kleinhans3Lova Chechik4Dominic Bartels5Michael Schmidt6Institute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany; Erlangen Graduate School in Advanced Optical Technologies (SAOT), Konrad-Zuse-Straße 3, 91052, Erlangen, Germany; Corresponding author. Institute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany.EOS GmbH Electro Optical Systems, Robert-Stirling-Ring 1, 82152, Krailling, Munich, GermanyEOS GmbH Electro Optical Systems, Robert-Stirling-Ring 1, 82152, Krailling, Munich, GermanyEOS GmbH Electro Optical Systems, Robert-Stirling-Ring 1, 82152, Krailling, Munich, GermanyInstitute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany; Erlangen Graduate School in Advanced Optical Technologies (SAOT), Konrad-Zuse-Straße 3, 91052, Erlangen, GermanyInstitute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany; Erlangen Graduate School in Advanced Optical Technologies (SAOT), Konrad-Zuse-Straße 3, 91052, Erlangen, GermanyInstitute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany; Erlangen Graduate School in Advanced Optical Technologies (SAOT), Konrad-Zuse-Straße 3, 91052, Erlangen, GermanyLaser-based powder bed fusion of metals (PBF-LB/M) enables the production of complex parts with high freedom of design. However, changes in cross-sectional area with build height influence inter-layer times and heat dissipation, resulting in potential local overheating. Since the temperature affects the microstructure and material properties, controlling the thermal history is necessary. To achieve this, a dynamic adjustment of energy input in response to the thermal conditions is required. Smart Fusion feedback-loop control monitors gray values recorded by optical tomography and compares them to a material and process specific target. If any deviations are identified, the system corrects them by applying locally varied laser power in the next layer. This study investigates the impact of the feedback-loop control on the microstructure evolution of titanium alloy Ti6Al4V and maraging steel MS1. Cuboids and complex parts with heat-accumulating features were manufactured using feedback-loop control and directly compared to their open-loop counterparts. Gray value profiles of the open-loop complex parts revealed large variations in temperature and geometry dependent differences in microstructure. The Smart Fusion feedback-loop control lead to a more constant temperature profile. In Ti6Al4V, this made the microstructure go from tempered martensite in the bulk section of the open-loop part to a consistent acicular martensitic structure in the feedback-loop controlled part. In MS1, the open-loop lead to signs of in-situ precipitation resulting in a significant local hardness increase in comparison to the feedback-loop control. Finally, the complex MS1 part could be built without minimum exposure times and uniform hardness of 350 HV0.5.http://www.sciencedirect.com/science/article/pii/S2238785424028175PBF-LB/MComplex structuresSmart FusionTi6Al4VMaraging steelMS1
spellingShingle Florian Nahr
Tobias Novotny
Dominik Kunz
Ulrich Kleinhans
Lova Chechik
Dominic Bartels
Michael Schmidt
Advanced process control in laser-based powder bed fusion–Smart Fusion feedback-loop control as a path to uniform properties for complex structures?
Journal of Materials Research and Technology
PBF-LB/M
Complex structures
Smart Fusion
Ti6Al4V
Maraging steel
MS1
title Advanced process control in laser-based powder bed fusion–Smart Fusion feedback-loop control as a path to uniform properties for complex structures?
title_full Advanced process control in laser-based powder bed fusion–Smart Fusion feedback-loop control as a path to uniform properties for complex structures?
title_fullStr Advanced process control in laser-based powder bed fusion–Smart Fusion feedback-loop control as a path to uniform properties for complex structures?
title_full_unstemmed Advanced process control in laser-based powder bed fusion–Smart Fusion feedback-loop control as a path to uniform properties for complex structures?
title_short Advanced process control in laser-based powder bed fusion–Smart Fusion feedback-loop control as a path to uniform properties for complex structures?
title_sort advanced process control in laser based powder bed fusion smart fusion feedback loop control as a path to uniform properties for complex structures
topic PBF-LB/M
Complex structures
Smart Fusion
Ti6Al4V
Maraging steel
MS1
url http://www.sciencedirect.com/science/article/pii/S2238785424028175
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