RESUMO

A two-dimensional, transient, axisymmetric model is developed to study the transport phenomena in a laser melting problem under a single laser pulse as well as repetitive laser pulse. The model is based on one-phase continuum mixture theory and fixed-grid technique. The model incorporates natural convection in the melt pool and radiation and convection heat losses from the irradiated surface. The complicated phase front evolution is captured implicitly by calculating the liquid volume fraction based on latent heat content at each control volume. An iterative update procedure is developed to update the liquid volume fraction at each control volume. A comparative study between the effect of natural convection and diffusion on the position and shape of the solid-liquid interface is made. It is found that natural convection does not play any significant role under the present condition in deciding the width and depth of the melt pool. The melt depth and melt radius predicted using the proposed model is compared with the available results and a good agreement is found. The model is further explored to investigate the effect of natural convection on the position and shape of the molten pool under the repetitive laser pulse.