Development and calibration of a CFD-based model of the bed fusion SLM additive manufacturing process aimed at optimising laser parameters

Abstract

The main concern deriving from the Selective Laser Melting technique is attaining a fully dense part out of the interconnected tracks. The right choice of process parameters is of fundamental importance to get a porosity free component. In this work a model has been developed simulating the printing process with the aim of creating a simple numerical tool for designing processing windows suitable to metal alloys of any composition. The applied simplified approach makes the model use as much practical as possible, while keeping the physical description representative. The model has been calibrated fitting experimental measures of track width, depth and cross sectional area taken from three literature sources, referring to: Ti6Al4V, Inconel 625 and Al7050. Effective liquid pool thermal conductivity, laser absorptivity and depth of application of laser energy are the fitting parameters. Laser absorptivity and depth of application of laser energy result to rise almost linearly with increasing specific energy; the slopes of the three analyzed alloys result very close to each other. The obtained results give confidence about the possibility of using the model as a predicting tool after further calibration on a wider range of metal alloys.