SMOB - Research project

Additive manufacturing laser fusion processes, are based on the interaction with the powder and the surface of the molten bath of a beam allowing the creation of a unitary bead whose quality and integrity are linked to the parameters (laser motion and, power, focussing, etc.) of the production devices. The technology concerned is Laser beam melting, the adjustment of the parameters of which can give rise to the generation of the “Keyhole” regime known from the welders community. This construction regime promoting the homogeneous distribution of the heat input can sometimes lead to the creation of macroscopic porosity type defects causing the weakening of the components thus produced. The mechanisms which lead to these defects are intrinsically linked to the laser-material interaction leading to the fusion of the powder and the substrate then to the evolution of the behavior of the liquid surface subjected to the tensions and pressure of the liquid in interaction with the external atmosphere. In this thesis, we study the formation of “keyhole” type defects by analysis of samples manufactured by the SLM process, on a well-controlled grade such as 316L stainless steel.