Quality assurance thermophysical aspects of highly porous implants with cellular structure obtained by selective laser melting

Selective laser melting (SLM) is an additive manufacturing process that involves the layer-by-layer construction of a three-dimensional object by local melting of a powder layer based on a prepared CAD model. This technology makes it possible to manufacture products of complex configuration, including internal channels of complex geometry. Such products include personalized highly porous implants, which are subject to very strict requirements in the field of elastic and strength properties, ensuring their compliance with the properties of the biological objects being replaced. The quality of highly porous cellular products formed by the selective laser melting method based on metal powder compositions is determined by a significant number of factors, the combined influence of which is difficult to control. At the same time, the structure and mechanical properties of highly porous cellular materials (HPCM) obtained by laser synthesis are largely determined by the melt bath shape stability, which depends on the ability of local heat dissipation, which in turn is determined by the fused product geometry. Under these conditions, simulation of thermal processes, including the prediction of the part fusion temperature modes, is of paramount importance. This study focuses on the numerical analysis of the powder layer thermophysical parameters during the laser melting process, which is difficult to analyze by direct measurements, and a computational model based on COMSOL Multiphysics has been created to predict the melt bath temperature field. The numerical model made it possible to quantify the influence of the selective laser melting process parameters (laser power and scanning speed) in combination with the choice of material and topology of the part on the temperature fields formation to determine the process technological parameter and the features of creating geometry for additive manufacturing, which make it possible to obtain products of proper quality. Cellular implants based on Ti6Al4V powder have been grown by selective laser melting.