Effects of rescanning parameters on densification and microstructural refinement of 316L stainless steel fabricated by laser powder bed fusion
Effects of rescanning parameters on densification and microstructural refinement of 316L stainless steel fabricated by laser powder bed fusion
A challenge with microstructural control and refinement in laser powder bed fusion (LPBF) is maintaining high density when choosing parameters for desired microstructures. Rescanning during LPBF has been reported to improve densification and decrease surface roughness for many different alloys. However, little has been reported regarding the effects of locally rescanning with varying processing parameters on sub-grain cell size refinement for 316L stainless steel (SS). This study presents a novel solution to enable high densification with microstructural control in 316L SS by using a set of initial scanning parameters to achieve densification and a different set of rescanning parameters to refine the microstructure. Results showed that rescanning resulted in heterogeneous microstructure with coarse cell size of 0.84 μm and locally refined cell size of 0.35 μm, while maintaining a high level of densification (99.96 %), therefore enabling potential variations in component strength and hardness. The spatial distribution of local microstructure refinement was dictated by the melt pool dimensions of initial scanning and rescanning relative to the powder layer thickness. To better understand the link between LPBF process parameters and microstructure, the Wilson-Rosenthal equation was used to predict cooling rate (G × R) and correlate with sub-grain cell size. Such variation in properties may be useful for applications requiring parts with hardened surfaces, or localized strengthening at stress concentrations and sites of expected failure.
316L stainless steel, Density, Heterogeneous microstructure, Laser powder bed fusion, Sub-grain cell size, Wilson-Rosenthal equation
Liang, Anqi
25257f89-cc17-42b8-81ac-fbf89b37738e
Hamilton, Andrew
9088cf01-8d7f-45f0-af56-b4784227447c
Polcar, Tomas
c669b663-3ba9-4e7b-9f97-8ef5655ac6d2
Pey, Khee Siang
8778e266-6482-4784-b840-9d3cbb982c9f
April 2022
Liang, Anqi
25257f89-cc17-42b8-81ac-fbf89b37738e
Hamilton, Andrew
9088cf01-8d7f-45f0-af56-b4784227447c
Polcar, Tomas
c669b663-3ba9-4e7b-9f97-8ef5655ac6d2
Pey, Khee Siang
8778e266-6482-4784-b840-9d3cbb982c9f
Liang, Anqi, Hamilton, Andrew, Polcar, Tomas and Pey, Khee Siang
(2022)
Effects of rescanning parameters on densification and microstructural refinement of 316L stainless steel fabricated by laser powder bed fusion.
Journal of Materials Processing Technology, [117493].
(doi:10.1016/j.jmatprotec.2022.117493).
Abstract
A challenge with microstructural control and refinement in laser powder bed fusion (LPBF) is maintaining high density when choosing parameters for desired microstructures. Rescanning during LPBF has been reported to improve densification and decrease surface roughness for many different alloys. However, little has been reported regarding the effects of locally rescanning with varying processing parameters on sub-grain cell size refinement for 316L stainless steel (SS). This study presents a novel solution to enable high densification with microstructural control in 316L SS by using a set of initial scanning parameters to achieve densification and a different set of rescanning parameters to refine the microstructure. Results showed that rescanning resulted in heterogeneous microstructure with coarse cell size of 0.84 μm and locally refined cell size of 0.35 μm, while maintaining a high level of densification (99.96 %), therefore enabling potential variations in component strength and hardness. The spatial distribution of local microstructure refinement was dictated by the melt pool dimensions of initial scanning and rescanning relative to the powder layer thickness. To better understand the link between LPBF process parameters and microstructure, the Wilson-Rosenthal equation was used to predict cooling rate (G × R) and correlate with sub-grain cell size. Such variation in properties may be useful for applications requiring parts with hardened surfaces, or localized strengthening at stress concentrations and sites of expected failure.
Text
Accepted Manuscript
- Accepted Manuscript
Text
Original Manuscript
- Accepted Manuscript
More information
Accepted/In Press date: 6 January 2022
e-pub ahead of print date: 15 January 2022
Published date: April 2022
Additional Information:
Funding Information:
This work was supported by the Faculty of Engineering and Physical Science at University of Southampton . The authors are also grateful for contributions of Dr. Dichu Xu (operation of Nanoindenter), Richard Dooler (operation of Concept Laser M2) and Geoff Howell (assistance with metallographic preparation).
Funding Information:
This work was supported by the Faculty of Engineering and Physical Science atUniversity of Southampton. The authors are also grateful for contributions of Dr. Dichu Xu (operation of Nanoindenter), Richard Dooler (operation of Concept Laser M2) and Geoff Howell (assistance with metallographic preparation).
Publisher Copyright:
© 2022 Elsevier B.V.
Keywords:
316L stainless steel, Density, Heterogeneous microstructure, Laser powder bed fusion, Sub-grain cell size, Wilson-Rosenthal equation
Identifiers
Local EPrints ID: 454139
URI: http://eprints.soton.ac.uk/id/eprint/454139
ISSN: 0924-0136
PURE UUID: c2068fb3-cf6c-4348-90ca-d6b56061c67f
Catalogue record
Date deposited: 01 Feb 2022 17:41
Last modified: 17 Mar 2024 07:03
Export record
Altmetrics
Contributors
Author:
Anqi Liang
Author:
Khee Siang Pey
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics