Deciphering the individual effects of the fluid flow and material evaporation physics on the melting characteristics and the re-solidification parameters during laser melting of solid Ti6Al4V substrate

Abstract

• Underlined individual effects of fluid flow and material evaporation separately. • Effect of adding various physics on the computational time consumption presented. • Four different models have been investigated for laser melting of Ti6Al4V. • Optimal numerical model for laser melting has been identified. • Detailed discussion on the solidification parameters in melt pool presented. In this study, the effect of inclusion of fluid flow and material evaporation physics in the thermal models of the laser melting process for Ti6Al4V has been compared to evaluate their individual influence on the simulation results and computational resources consumed. Though the study seems basic, it aims to address the important issue of increase in the computational resources consumption and time when these physics are added to the model. The study also focuses upon finding an optimized model that can enable faster prediction of thermal and melt pool dimension results for macro-scale laser melting cases, while ensuring the accuracy of these results against the experimental observations. It was seen that the fluid flow and material evaporation assisted each other in some aspects and opposed in some others, but the extent of their individual effects varied significantly in the magnitudes. Along with the individual melt pool characteristics comparison, the thermal field along the length, width and depth of the computational domain as well as the computational time consumed by each simulation are also compared for different models. It is obtained through experimental validation that material evaporation could reduce the reliance on the fluid flow inclusion in the model to accurately predict the melt pool dimensions, that too while consuming drastically less computational time. Through these comparisons and experimental validation, an optimized model has been identified, which is then used to present a parametric analysis of the solidification variables (G, R, GR and G/R) for the laser melting of Ti6Al4V.