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...
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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 |
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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 |
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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. |
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School of Mechanical and Aerospace Engineering |
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School of Mechanical and Aerospace Engineering Tang, Chao Tan, Jie Lun Wong, Chee How |
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Article |
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Tang, Chao Tan, Jie Lun Wong, Chee How |
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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 |
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1681057833790996480 |