Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/102525
Title: A numerical investigation on the physical mechanisms of single track defects in selective laser melting
Authors: Tang, Chao
Tan, Jie Lun
Wong, Chee How
Keywords: Computational Fluid Dynamics
Heat Transfer
Engineering::Mechanical engineering
Issue Date: 2018
Source: 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
Series/Report no.: International Journal of Heat and Mass Transfer
Abstract: 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.
URI: https://hdl.handle.net/10356/102525
http://hdl.handle.net/10220/49952
ISSN: 0017-9310
DOI: http://dx.doi.org/10.1016/j.ijheatmasstransfer.2018.06.073
Rights: © 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.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:MAE Journal Articles
SC3DP Journal Articles

Files in This Item:
File Description SizeFormat 
Manuscript.pdf2.68 MBAdobe PDFThumbnail
View/Open

Google ScholarTM

Check

Altmetric

Items in DR-NTU are protected by copyright, with all rights reserved, unless otherwise indicated.