A numerical investigation on the physical mechanisms of single track defects in selective laser melting
By C. Tang, J. Tan, C. Wong. International Journal of Heat and Mass Transfer, 2018
275 citations recorded by the source corpus.
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.
Subfields: Mechanical Engineering, Mechanics of Materials
View Paper: https://www.semanticscholar.org/paper/45853ebe6a5d9d771b6df1efc9c79f604fe65b29
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In Mechanical Engineering
In Mechanics of Materials
Citations in the corpus
- Mechanism of keyhole pore formation in metal additive manufacturing (2021, background): “The simulation by Tang et al.(27) indicated that the spherical pores at the bottom of the molten pool formed as the energy density increased during AM.”
- Optimization and comparison of porosity rate measurement methods of Selective Laser Melted metallic parts (2019, result): “The increase in porosity rate observed at high VED, and assumed to be due to the destabilization of the key-hole welding mode is in full agreement with a recent simulation work by Tang [35].”
- Keyhole-induced porosities in Laser-based Powder Bed Fusion (L-PBF) of Ti6Al4V: High-fidelity modelling and experimental validation (2019, background): “[28] studied the keyhole formation with a high-fidelity model for a L-PBF of a stainless steel.”