Flow and element mixing characteristics in lase-GMA hybrid welding

Three dimensional numerical simulations are performed to analyze the fluid flow and mixing of alloying element in laser-gas metal arc (GMA) hybrid welding in full penetration welding with GMA leading configuration. Navier stoke's, continuity, energy and volume of fluid (VOF) equations are solved alogwith auxilary models for laser and GMA heat sources. Laser welding is considered using real time multiple reflection models using commerciallly avaialble flow software. The results are compared with experimentally obtained bead shape and the results are found to be in fair agreement. Two distinct flow patterns are found in upper and root surface of workpiece. The incoming metal mostly mixed in molten pool on upper surface therefore higher concentration of Cr is found in upper part of bead. Experimentally obtained EDS scans of Cr shows that mixing is higher in upper part of bead and this fact is also depicted in simulation but the amount of Cr of mixing would vary with location. Higher concentration is expected near the point of laser stoppage.