3D heat transfer, fluid flow and electromagnetic model for cold metal transfer wire arc additive manufacturing (Cmt-Waam)

Abstract

Abstract In this paper, we present a 3D numerical model of Wire Arc Additive Manufacturing to simulate the material deposition and the temperature field from the operating parameters. This predictive model, applied to a Cold Metal Transfer (CMT) process, takes into account electromagnetism, fluid flow and heat transfer in all domains (wire, arc, melt pool, substrate). This model, developed using COMSOL Multiphysics® software, calculates the creation of the molten metal drop at the filler wire tip, the detachment of the drop when the filler material retracts during the short circuiting phase and the growth of the deposit. This innovative work describes for the first time the wire behaviour dynamically and its interaction with the melt pool in 3D in a fully coupled approach. The dynamics of the free surface are treated with the level set method, particularly efficient for strong topological changes. The Lorentz forces, shear stress, arc pressure, and Joule effect are calculated. This model requires only the knowledge of the operating parameters without any assumption on the arc distribution. It aims to simulate the build-up of a 304 stainless steel wall. To validate this model, the melt pool dimensions and shape of the deposit calculated for the first layer are compared to experimental data given by macrographs and high speed videos.