Development and validation of a material evaporation assisted thermal model for time-efficient calculation of thermal and solidification parameters during laser powder bed fusion process for Ti6Al4V

Abstract

The computational models used to study the laser powder bed fusion (LPBF) process incorporate numerous physics that make the model heavy and time consuming, rendering them unfit to run large scale LPBF simulations, such as multi-track/multi-layer LPBF or thermo-mechanical analyses. Hence, a new computational model has been proposed for the LPBF of Ti6Al4V, which incorporated material evaporation and heat source modification to accurately predict the melt pool characteristics without including the melt pool hydrodynamics in the model. The omission of the hydrodynamics allowed the model to run faster and consume less computational time, while the material evaporation and heat source modification facilitated reliable prediction of the temperature field and melt pool dimensions. The heat source has been modified by coupling the heat source depth with process parameters through multiple regression analyses on the experimental and numerical results and applying material evaporation as a heat loss flux. The proposed model has been validated by comparing the simulation results with experimental data and simulation results considering melt pool hydrodynamics. It was seen that proposed model predicted melt pool dimensions with very high accuracy against the experiments (−2.76% in depth and +7.68% in width) while consuming nearly 1/100th of the time consumed by model with fluid flow. The present model, therefore, proved its potential for application in large scale LPBF simulations mentioned earlier and can also be combined with other physics that do not require melt pool hydrodynamic details, such as the thermo-mechanical studies.