Numerical analysis of the effect of processing parameters on the microstructure of stainless steel 316L manufactured by laser-based powder bed fusion

Abstract

Additive manufacturing is a highly projected technology that continues to evolve and improve. In this context, laser-based powder bed fusion (L-PBF) offers a series of advantages for manufacturing parts of high geometric complexity, impossible or too costly to process through conventional processes. However, anticipating the effect of processing parameters on the resulting microstructure remains challenging due to the complexity of the involved processes. In this sense, numerical simulation, also substantially improved in the recent decade, in particular finite element analysis, offers considerable precision, comparable to results obtained by experimentation. Therefore, in this work, the applicability of numerical simulation is evaluated to predict the effect of laser power, scanning speed, and hatch spacing on the dimensions of the molten pool, degree of porosity, and the resulting microstructure. Ansys Additive package was employed to simulate a single bed deposit, evaluate the porosity, and determine the microstructure of the 316L stainless steel processed through L-PBF. The results indicate that the lowest degree of porosity is obtained with high laser power, low scanning speed, and the lowest hatch spacing with a recommendable volumetric energy density greater than 60 J/mm3. Through the simulation of the microstructure, it was possible to obtain information on the thermal gradient, solidification rate, and melt pool characteristics. Ansys Additive proves a powerful tool to understand microstructure evolution and furthering customization of mechanical properties.