Development and application of a simplified thermo-evaporative multi-track laser powder bed fusion model for Ti6Al4V

Abstract

Often the parametric analyses of the laser powder bed fusion (LPBF) process are concerned with laser power or scan speed, and other parameters such as scan spacing are paid lesser attention, particularly due to the huge computational power required for their investigation. Hence, in this study a simple and efficient thermo-evaporative model is developed for multi-track LPBF that excluded the solution of melt pool flow dynamics and thus enabled faster and economic simulation of the problem. Material evaporation was added to control the temperature rise up to reasonable levels, which acted only as a heat loss flux on the top boundary. The model has been first validated against the single track results and then applied to multi-track modeling for several different values of scan spacing while other parameters are kept constant. The study showed the potential of the developed thermo-evaporative model in simulating the multi-track problem and conducting a parametric analysis concerning the variation of scan spacing. The results were verified against the experimental results at a higher scan spacing where the computed and experimental porosities were compared qualitatively, and it was observed that the proposed model predicted the lack of melting porosity very well. The temperature field and other thermal characteristics such as thermal gradients and heating/cooling rates were calculated and discussed as well.