Part-scale numerical simulation for laser-powder directed energy deposition: experimental calibration

Abstract To increase the environmental sustainability of products, the repair and refurbishment of damaged or obsolete components can be carried out using additive manufacturing (AM) processes. The Laser-powder directed energy deposition (LP-DED) process is an interesting candidate due to its many potential applications, particularly for the repair of metal parts. For a more thorough knowledge and understanding of the process, numerical approaches are necessary to avoid extensive and costly experimental campaigns. In this work, an original 3D thermal FEM model is proposed to predict the temperature during the LP-DED process at the macroscopic scale. The numerical simulation was based on the layer-by-layer method using an equivalent volumetric heat source and then using the superlayer method. The predicted temperature is compared with experimental temperature measurements during the deposition of stainless steel (316L) single-bead walls and multi-layer squares. The experimental results showed the influence of process parameters and deposition strategy on the temperature, which reached a maximum around 220 °C. The numerical simulation showed an overestimation of the temperature of about 120 to 200 °C compared to the experiments for all the tests carried out. A correction factor was applied to the numerical heat source which allowed to reduce the discrepancies to 50 °C. Finally, the superlayer approach led to a reduction of computational time at the expense of accuracy. Current limitations highlighted the importance of the definition of the equivalent heat source definition and boundary conditions. The chosen approach (layer-by-layer vs. superlayer) depends on the applications and the studied geometry.