Product Code: JLA_24_3_032008

Authors:
Simon Morville
Muriel Carin
LIMATB, Universite´ de Bretagne-Sud/UEB, Centre de recherche Ch. Huygens, Rue de Saint Maude´, BP 92116, 56321 Lorient cedex, France

Patrice Peyre
Myriam Gharbi
PIMM, UMR 8006 CNRS-Arts et Me´tiers Paris Tech, 151 Boulevard de l’Hoˆpital, 75013 Paris, France

Denis Carron
Philippe Le Masson
LIMATB, Universite´ de Bretagne-Sud/UEB, Centre de recherche Ch. Huygens, Rue de Saint Maude´, BP 92116, 56321 Lorient cedex, France

Re´my Fabbro
PIMM, UMR 8006 CNRS-Arts et Me´tiers Paris Tech, 151 Boulevard de l’Hoˆpital, 75013 Paris, France

Derived from laser cladding, the direct laser metal deposition (DLMD) process is based upon a laser beam–powder–melt pool interaction and enables the manufacturing of complex 3D shapes much faster than conventional processes. However, the surface finish remains critical, and DLMD parts usually necessitate postmachining steps. Within this context, the focus of our work is to improve the understanding of the phenomena responsible for deleterious surface finish by using numerical simulation. Mass, momentum, and energy conservation equations are solved using comsol multiphysics^® in a 2D transient model including filler material with surface tension and thermocapillary effects at the free surface. The dynamic shape of the molten zone is explicitly described by a moving mesh based on an arbitrary Lagrangian–Eulerian method (ALE). This model is used to analyze the influence of the process parameters, such as laser power, scanning speed, and powder feed rate on the melt pool behavior. The simulations of a single layer and multilayer claddings are presented. The numerical results are compared with experimental data, in terms of layer height, melt pool length, and depth of penetration, obtained from high speed camera. The experiments are carried out on a widely used aeronautical alloy (Ti–6Al–4 V) using a Nd:YAG laser. The results show that the dilution ratio increases with increasing the laser power and the scanning velocity or with decreasing the powder feed rate. The final surface finish is then improved.