Selective Laser Melting of 316L Austenitic Stainless Steel: Detailed Process Understanding Using Multiphysics Simulation and Experimentation

Abstract

The parameter sets used during the selective laser melting (SLM) process directly affect the final product through the resulting melt-pool temperature. Achieving the optimum set of parameters is usually done experimentally, which is a costly and time-consuming process. Additionally, controlling the deviation of the melt-pool temperature from the specified value during the process ensures that the final product has a homogeneous microstructure. This study proposes a multiphysics numerical model that explores the factors affecting the production of parts in the SLM process and the mathematical relationships between them, using stainless steel 316L powder. The effect of laser power and laser spot diameter on the temperature of the melt-pool at different scanning velocities were studied. Thus, mathematical expressions were obtained to relate process parameters to melt-pool temperature. The resulting mathematical relationships are the basic elements to design a controller to instantly control the melt-pool temperature during the process. In the study, test samples were produced using simulated parameters to validate the simulation approach. Samples produced using simulated parameter sets resulting in temperatures of 2000 K and above had acceptable microstructures. Evaporation defects caused by extreme temperatures, unmelted powder defects due to insufficient temperature, and homogenous microstructures for suitable parameter sets predicted by the simulations were obtained in the experimental results, and the model was validated.

Advances in Laser Additive Manufacturing of Cobalt–Chromium Alloy Multi-Layer Mesoscopic Analytical Modelling with Experimental Correlations: From Micro-Dendrite Grains to Bulk Objects

“…The additive manufacturing (AM) process can produce three-dimensional (3D) parts, by utilizing layer-upon-layer technique, via a computer-aided design (CAD) model [ 1 ]. AM has been successfully applied in medical [ 2 , 3 ], aerospace [ 4 ], automotive [ 5 ], and various industrial applications [ 6 ]. The Hall–Petch relationship identifies that the material’s active strength depends on the grain size such that strength elevated by decreasing the average grain size [ 7 ].…”

Full-Field Mapping and Flow Quantification of Melt Pool Dynamics in Laser Powder Bed Fusion of SS316L

“…It is noted that many variables affect the melt pool, and indirectly, the performance of the components manufactured [ 14 ], including scanning velocity, laser power, particle size distribution (PSD), and layer thickness [ 15 ]. Concerning the effecting process variables, systematic efforts were made to explain the complicated melt pool dynamics [ 12 , 16 , 17 , 18 , 19 ], process parameters, and frequent defects.…”

“…The results reveal that the instability of the melt pool and keyhole triggered the generation of the voids. Most of the computational models listed above focus primarily on exploring the effect of different parameters [ 15 , 35 , 36 , 37 , 38 , 39 ]. In recent years, extensive studies have centered on the production of defects during the LPBF process [ 18 , 19 , 40 ].…”

Laser Melting Deposition Additive Manufacturing of Ti6Al4V Biomedical Alloy: Mesoscopic In-Situ Flow Field Mapping via Computational Fluid Dynamics and Analytical Modelling with Empirical Testing

“…Laser additive manufacturing (LAM) is a subtype of additive manufacturing (AM) that fuses the powder particles with a laser beam to generate high-quality metallic parts [7]. LAM has the quickest annual growth of all AM methods and is used in various industries, including automobile, space, healthcare and energy [8][9][10][11][12][13]. Laser metal deposition (LMD) is a sub-branch of AM with various applications, including surface treatment and coatings [14], the production of functionally graded materials [15] and restoration of broken parts [16].…”