High-vacuum laser treatments enhance strength, ductility and fatigue limit of additively manufactured stainless steel

Post-process laser scanning under high vacuum is proposed as a non-isothermal heat treatment to simultaneously refine the intragranular microstructure near the surface and reduce surface roughness, while preventing oxidation, to enhance the mechanical response of an alloy. This treatment is performe...

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Main Authors: Juan Guillermo Santos Macías, Kewei Chen, Alexandre Tanguy, Nathalie Isac, Maxime Vallet, Louis Cornet, Vincent Michel, Manas Vijay Upadhyay
Format: Article
Language:English
Published: Elsevier 2025-06-01
Series:Materials & Design
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Online Access:http://www.sciencedirect.com/science/article/pii/S0264127525004848
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author Juan Guillermo Santos Macías
Kewei Chen
Alexandre Tanguy
Nathalie Isac
Maxime Vallet
Louis Cornet
Vincent Michel
Manas Vijay Upadhyay
author_facet Juan Guillermo Santos Macías
Kewei Chen
Alexandre Tanguy
Nathalie Isac
Maxime Vallet
Louis Cornet
Vincent Michel
Manas Vijay Upadhyay
author_sort Juan Guillermo Santos Macías
collection DOAJ
description Post-process laser scanning under high vacuum is proposed as a non-isothermal heat treatment to simultaneously refine the intragranular microstructure near the surface and reduce surface roughness, while preventing oxidation, to enhance the mechanical response of an alloy. This treatment is performed using laser spot sizes and scan speeds that produce higher temperature gradients and faster heating/cooling rates than those encountered during manufacturing. The effectiveness of this approach is demonstrated on laser-based direct energy deposited 316L stainless steel using parameters similar to those used in laser-based powder bed fusion. High vacuum (< 0.1 Pa) lasering is conducted inside a newly integrated continuous-wave laser and scanning electron microscope (CW Laser-SEM). The treatments result in an order-of-magnitude reduction in microsegregation cell sizes (from 2.2 to 0.3 µm) coinciding with 0.3 µm-diameter dense-walled dislocation cell structures, as well as in surface roughness (from 16.6 to 0.9 µm) of LDED 316L. For a parameter set in which the laser penetrates 14% of total depth (7% each on the two widest sample surfaces), significant enhancements are obtained in yield strength (31.11%), ductility (14.2%) and fatigue limit (25%). This approach has tremendous potential to alter microstructure and improve mechanical response of additively and conventionally manufactured alloys.
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spelling doaj-art-eaa02bd7d206493480f2d6c592f365642025-08-20T03:10:42ZengElsevierMaterials & Design0264-12752025-06-0125411406410.1016/j.matdes.2025.114064High-vacuum laser treatments enhance strength, ductility and fatigue limit of additively manufactured stainless steelJuan Guillermo Santos Macías0Kewei Chen1Alexandre Tanguy2Nathalie Isac3Maxime Vallet4Louis Cornet5Vincent Michel6Manas Vijay Upadhyay7Laboratoire de Mécanique des Solides (LMS), CNRS, École Polytechnique, Institut Polytechnique de Paris, Route de Saclay, 91120 Palaiseau, France; Corresponding authors.Laboratoire de Mécanique des Solides (LMS), CNRS, École Polytechnique, Institut Polytechnique de Paris, Route de Saclay, 91120 Palaiseau, FranceLaboratoire de Mécanique des Solides (LMS), CNRS, École Polytechnique, Institut Polytechnique de Paris, Route de Saclay, 91120 Palaiseau, FranceLaboratoire de Mécanique des Solides (LMS), CNRS, École Polytechnique, Institut Polytechnique de Paris, Route de Saclay, 91120 Palaiseau, FranceUniversité Paris-Saclay, CentraleSupélec, ENS Paris-Saclay, CNRS, LMPS - Laboratoire de Mécanique Paris-Saclay, 91190 Gif-sur-Yvette, France; Université Paris-Saclay, CentraleSupélec, CNRS, Laboratoire SPMS - Structures, Propriétés et Modélisation des Solides, 91190 Gif-sur-Yvette, FranceUniversité Paris-Saclay, CentraleSupélec, ENS Paris-Saclay, CNRS, LMPS - Laboratoire de Mécanique Paris-Saclay, 91190 Gif-sur-Yvette, FranceLaboratoire de Procédés et Ingénierie en Mécanique et Matériaux (PIMM), CNRS UMR 8006, Arts et Métiers Institute of Technology, HESAM University, 151 Boulevard de l’Hôpital, 75013 Paris, FranceLaboratoire de Mécanique des Solides (LMS), CNRS, École Polytechnique, Institut Polytechnique de Paris, Route de Saclay, 91120 Palaiseau, France; Corresponding authors.Post-process laser scanning under high vacuum is proposed as a non-isothermal heat treatment to simultaneously refine the intragranular microstructure near the surface and reduce surface roughness, while preventing oxidation, to enhance the mechanical response of an alloy. This treatment is performed using laser spot sizes and scan speeds that produce higher temperature gradients and faster heating/cooling rates than those encountered during manufacturing. The effectiveness of this approach is demonstrated on laser-based direct energy deposited 316L stainless steel using parameters similar to those used in laser-based powder bed fusion. High vacuum (< 0.1 Pa) lasering is conducted inside a newly integrated continuous-wave laser and scanning electron microscope (CW Laser-SEM). The treatments result in an order-of-magnitude reduction in microsegregation cell sizes (from 2.2 to 0.3 µm) coinciding with 0.3 µm-diameter dense-walled dislocation cell structures, as well as in surface roughness (from 16.6 to 0.9 µm) of LDED 316L. For a parameter set in which the laser penetrates 14% of total depth (7% each on the two widest sample surfaces), significant enhancements are obtained in yield strength (31.11%), ductility (14.2%) and fatigue limit (25%). This approach has tremendous potential to alter microstructure and improve mechanical response of additively and conventionally manufactured alloys.http://www.sciencedirect.com/science/article/pii/S0264127525004848Laser treatmentMechanical behaviourElectron microscopyFatigue3D printingAM 316L
spellingShingle Juan Guillermo Santos Macías
Kewei Chen
Alexandre Tanguy
Nathalie Isac
Maxime Vallet
Louis Cornet
Vincent Michel
Manas Vijay Upadhyay
High-vacuum laser treatments enhance strength, ductility and fatigue limit of additively manufactured stainless steel
Materials & Design
Laser treatment
Mechanical behaviour
Electron microscopy
Fatigue
3D printing
AM 316L
title High-vacuum laser treatments enhance strength, ductility and fatigue limit of additively manufactured stainless steel
title_full High-vacuum laser treatments enhance strength, ductility and fatigue limit of additively manufactured stainless steel
title_fullStr High-vacuum laser treatments enhance strength, ductility and fatigue limit of additively manufactured stainless steel
title_full_unstemmed High-vacuum laser treatments enhance strength, ductility and fatigue limit of additively manufactured stainless steel
title_short High-vacuum laser treatments enhance strength, ductility and fatigue limit of additively manufactured stainless steel
title_sort high vacuum laser treatments enhance strength ductility and fatigue limit of additively manufactured stainless steel
topic Laser treatment
Mechanical behaviour
Electron microscopy
Fatigue
3D printing
AM 316L
url http://www.sciencedirect.com/science/article/pii/S0264127525004848
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