Effect of process parameter on turbulent transport in a laser surface alloying process

Abstract

A three-dimensional, transient numerical model is used for analyzing turbulent momentum, heat, and mass transport in typical laser surface alloying processes. The Reynolds averaged conservation equations are solved using a finite volume approach. The turbulent transport is accounted for by a suitably modified high Reynolds number k-ε model in the presence of a continuously evolving phase-change interface. Phase change aspects of the problem are addressed using a modified enthalpy-porosity technique. Subsequently, the developed turbulent transport model is used to simulate single pass laser surface alloying processes with different sets of processing parameters, such as laser power, scanning speed, and powder feedrate, in order to assess their influences on molten pool geometry and dynamics, cooling rates, as well as on species concentration distribution inside the substrate. In order to investigate the effects of turbulence, the parametric studies for the present turbulent simulation are compared with corresponding laminar simulation results. Significant differences are observed on comparing the laminar and turbulent simulation results, which provide valuable insights for controlling the process parameters based on the manufacturing needs.