A numerical investigation on the physical mechanisms of single track defects in selective laser melting

A three-dimensional high-fidelity model was developed to simulate the single track formation of stainless steel 316L during selective laser melting. Different laser powers and scanning speeds were adopted to perform the numerical simulations, revealing the underlying physics of porosity development...

Full description

Saved in:
Bibliographic Details
Main Authors: Tang, Chao, Tan, Jie Lun, Wong, Chee How
Other Authors: School of Mechanical and Aerospace Engineering
Format: Article
Language:English
Published: 2019
Subjects:
Online Access:https://hdl.handle.net/10356/102525
http://hdl.handle.net/10220/49952
Tags: Add Tag
No Tags, Be the first to tag this record!
Institution: Nanyang Technological University
Language: English
id sg-ntu-dr.10356-102525
record_format dspace
spelling sg-ntu-dr.10356-1025252020-09-26T22:06:32Z A numerical investigation on the physical mechanisms of single track defects in selective laser melting Tang, Chao Tan, Jie Lun Wong, Chee How School of Mechanical and Aerospace Engineering Singapore Centre for 3D Printing Computational Fluid Dynamics Heat Transfer Engineering::Mechanical engineering A three-dimensional high-fidelity model was developed to simulate the single track formation of stainless steel 316L during selective laser melting. Different laser powers and scanning speeds were adopted to perform the numerical simulations, revealing the underlying physics of porosity development during the melting and solidification process. Our studies suggest the importance of surface tension and recoil pressure in creating two types of porosities: near-spherical and irregular-shaped porosities. With excessive energy intensity, the predominant recoil pressure is liable to create a deep moving keyhole, resulting in entrapped gas bubbles with near-spherical geometries underneath the solidified track. Additionally, wetting behaviour between melted powders and the substrate below is proved to be significant in eliminating interlayer porosities with irregular configurations. A low energy intensity is possibly inadequate to melt the substrate below, suppressing the wetting behaviour and giving rise to the formation of interlayer defects. Furthermore, our multilayer simulations prove that the surface roughness of previously solidified layer plays a critical role in affecting the local thickness of next powder layer. The fluctuation of local powder thickness is probably associated with the formation of interlayer defects, as the energy intensity maybe not strong enough to penetrate a locally thicker powder layer. NRF (Natl Research Foundation, S’pore) Accepted version 2019-09-18T04:56:58Z 2019-12-06T20:56:27Z 2019-09-18T04:56:58Z 2019-12-06T20:56:27Z 2018 Journal Article Tang, C., Tan, J., & Wong, C. (2018). A numerical investigation on the physical mechanisms of single track defects in selective laser melting. International Journal of Heat and Mass Transfer, 126957-968. doi:10.1016/j.ijheatmasstransfer.2018.06.073 0017-9310 https://hdl.handle.net/10356/102525 http://hdl.handle.net/10220/49952 10.1016/j.ijheatmasstransfer.2018.06.073 en International Journal of Heat and Mass Transfer © 2018 Elsevier. All rights reserved. This paper was published in International Journal of Heat and Mass Transfer and is made available with permission of Elsevier. 40 p. application/pdf
institution Nanyang Technological University
building NTU Library
country Singapore
collection DR-NTU
language English
topic Computational Fluid Dynamics
Heat Transfer
Engineering::Mechanical engineering
spellingShingle Computational Fluid Dynamics
Heat Transfer
Engineering::Mechanical engineering
Tang, Chao
Tan, Jie Lun
Wong, Chee How
A numerical investigation on the physical mechanisms of single track defects in selective laser melting
description A three-dimensional high-fidelity model was developed to simulate the single track formation of stainless steel 316L during selective laser melting. Different laser powers and scanning speeds were adopted to perform the numerical simulations, revealing the underlying physics of porosity development during the melting and solidification process. Our studies suggest the importance of surface tension and recoil pressure in creating two types of porosities: near-spherical and irregular-shaped porosities. With excessive energy intensity, the predominant recoil pressure is liable to create a deep moving keyhole, resulting in entrapped gas bubbles with near-spherical geometries underneath the solidified track. Additionally, wetting behaviour between melted powders and the substrate below is proved to be significant in eliminating interlayer porosities with irregular configurations. A low energy intensity is possibly inadequate to melt the substrate below, suppressing the wetting behaviour and giving rise to the formation of interlayer defects. Furthermore, our multilayer simulations prove that the surface roughness of previously solidified layer plays a critical role in affecting the local thickness of next powder layer. The fluctuation of local powder thickness is probably associated with the formation of interlayer defects, as the energy intensity maybe not strong enough to penetrate a locally thicker powder layer.
author2 School of Mechanical and Aerospace Engineering
author_facet School of Mechanical and Aerospace Engineering
Tang, Chao
Tan, Jie Lun
Wong, Chee How
format Article
author Tang, Chao
Tan, Jie Lun
Wong, Chee How
author_sort Tang, Chao
title A numerical investigation on the physical mechanisms of single track defects in selective laser melting
title_short A numerical investigation on the physical mechanisms of single track defects in selective laser melting
title_full A numerical investigation on the physical mechanisms of single track defects in selective laser melting
title_fullStr A numerical investigation on the physical mechanisms of single track defects in selective laser melting
title_full_unstemmed A numerical investigation on the physical mechanisms of single track defects in selective laser melting
title_sort numerical investigation on the physical mechanisms of single track defects in selective laser melting
publishDate 2019
url https://hdl.handle.net/10356/102525
http://hdl.handle.net/10220/49952
_version_ 1681057833790996480