MODELING OF TURBULENT TRANSPORT IN LASER SURFACE ALLOYING

Abstract

A three-dimensional, transient model is developed in order to address the turbulent transport in a typical laser surface alloying process. Turbulent melt-pool convection is taken into account by using a suitably modified high-Reynolds-number k–ɛ model in the presence of a continuously evolving phase-change interface. The phase-change aspects of the problem are addressed using a modified enthalpy-porosity technique. This newly developed mathematical model is subsequently utilized to simulate a typical high-power laser surface alloying process, where effects of turbulent transport can actually be realized. In order to investigate the effects of turbulence on laser molten pool convection, simulations with laminar and turbulent transport are carried out for some problem parameters. Significant differences in the molten pool morphology are observed on comparing the laminar and turbulent simulation results. It is also revealed that turbulent simulations yield a much better match with the experimentally obtained species concentration distribution within the alloyed layer, compared to that in corresponding laminar simulations.