The Marangoni effect on microstructure properties and morphology of laser-treated Al-Fe alloy with single track by FEM: Varying the laser beam velocity

Abstract

Laser workpiece surface treatment of Al-1.5 wt% Fe alloy with single track was performed with a 2 kW Yb-fiber laser (IPG YLR-2000S). A 3D thermal FEM model has been built to calculate the temperature field and fluid flow field in the molten pool cross-section. Results of numerical simulation, experimental of the micrographs and morphologies were presented, discussed and checked. By FEM the fluid flow due to the Marangoni effect presents two symmetric vortices corresponding to the molten pool center line. The Marangoni effect can lead to mass transfer and interfacial turbulence, when this phenomenon is considered, maximum values of the flow velocity and as well as thermal gradient occur around on the workpiece surface, smaller velocity and thermal gradient occur in the melt pool-substrate interface, thus, the Marangoni effect was more noticeable in lower than in high laser beam velocities. This phenomenon influences and controls the quality, such as, properties of the microstructure, morphological characteristic and as well as quality of laser-treated workpiece tracks, therefore, at low laser beam velocities the morphology is higher and quality of track presents many defects than at high laser beam velocities. Simulation results were assessed with the experimental data, their results were fairly coherent.