Investigation into microstructure and element segregation of Inconel 713LC during SLM processing using modified cellular automaton model

Abstract

A numerical and experimental investigation is performed into the feasibility of fabricating IN713LC components using selective laser melting (SLM) through an appropriate control of the solidification speed, microstructure formation and element segregation. A modified Cellular Automaton (CA) model is developed to explore the nucleation, grain growth and element segregation behavior of IN713LC during ultra-fast solidification. It is found that the undesired phase formation which occurs during SLM processing of IN713LC is caused by the micro segregation of Nb, Ti, Mo and C at the grain boundaries. It is further shown that the micro segregation intensity depends on the solidification speed, which is determined in turn by the laser energy density. In particular, a lower laser energy density increases the solidification speed and results in a more uniform solid phase, thereby reducing the risk of crack formation. The simulation results are verified by experimental investigation. The results confirm that a lower laser energy density reduces the crack density and crack length. Finally, a crack-free IN713LC SLM sample is successfully produced by reducing the energy density from 360 to 170 J/m.