Process Optimization for CMT and SLM Metal Additive Manufacturing

Metal additive manufacturing techniques offer a number of advantages in the aerospace and biotechnology industries. However, the technique has several drawbacks, such as residual stresses and porosity, especially in Cold Metal Transfer (CMT). Some defects, such as cracks, are specific to the SLM method. These can have catastrophic effects on the mechanical properties of manufactured parts. A method to minimize or even eliminate these defects is thus necessary. Many causes are common to several defects in metal parts manufactured using the above techniques. Among the causes are surface finish (laser scanning speed, deposited powder thickness, laser power), porosity (process, alloy component evaporation, impurities, low laser energy absorption…), and the balling effect, characterized by the formation of coarse droplets of molten metal, which are caused by the atmosphere in the combustion chamber or the wettability of the solid material by the liquid material. Therefore, the objective of this work is to master metal additive manufacturing processes (SLM and CMT) by controlling defects in these processes and to study the materials in order to improving their properties.