Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones

By S. Khairallah, A. Anderson, A. Rubenchik, Wayne E. King. 2015

2,480 citations recorded by the source corpus.

Abstract This study demonstrates the significant effect of the recoil pressure and Marangoni convection in laser powder bed fusion (L-PBF) of 316L stainless steel. A three-dimensional high fidelity powder-scale model reveals how the strong dynamical melt flow generates pore defects, material spattering (sparking), and denudation zones. The melt track is divided into three sections: a topological depression, a transition and a tail region, each being the location of specific physical effects. The inclusion of laser ray-tracing energy deposition in the powder-scale model improves over traditional volumetric energy deposition. It enables partial particle melting, which impacts pore defects in the denudation zone. Different pore formation mechanisms are observed at the edge of a scan track, at the melt pool bottom (during collapse of the pool depression), and at the end of the melt track (during laser power ramp down). Remedies to these undesirable pores are discussed. The results are validated against the experiments and the sensitivity to laser absorptivity is discussed.

Subfields: Automotive Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/dfcf48cf14b6a210ec96578843d355c867b1ea7b

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Automotive Engineering

1. T. DebRoy
2. T. Mukherjee
3. H. Wei
4. Amitava De
5. Wei Zhang
6. S. M. Yusuf
7. N. Gao
8. Swee Leong Sing

In Mechanical Engineering

1. T. DebRoy
2. T. Mukherjee
3. H. Wei
4. Amitava De
5. Wei Zhang
6. Swee Leong Sing
7. J. Elmer
8. W. Y. Yeong

Citations in the corpus

• Experimental analysis of spatter generation and melt-pool behavior during the powder bed laser beam melting process (2018, background): “Khairallah et al. (2016) also considered key-hole closure as a possible explanation for porosity formation, and confirmed that melt-pool vaporization was a key factor for the formation of spatters and denudation.”
• Influence of SLM process parameters on the surface finish, porosity rate and fatigue behavior of as-built Inconel 625 parts (2017, background): “Sa results presented here above mostly traduce the in-fl uence of scan speed at constant laser power: lower scan speed promote large but turbulent melt-pools which deteriorate surface fi nish, by increasing the amount of agglomerated spatters particles on the built surfaces (Khairallah et al., 2016).”
• Influence of energy density on metallurgy and properties in metal additive manufacturing (2017, background): “Spatter ejection occurs due to the overheating of molten pool as a result of the high energy beamfeedstock material interaction during metal AM processing, which creates recoil pressure in the molten pool due to convective transport of fluid (Marangoni Convection) [22,107,114].”
• Microstructure modelling for metallic additive manufacturing: a review (2020, methodology): “Most FVM models only simulate a single melt track in 3D (Fallah et al. 2012; Lee and Zhang 2015; Khairallah et al. 2016; Panwisawas et al. 2017).”