Analysis of Enhanced Thermal Conductivity Approach for Predicting Melt Pool Geometry and Temperature Distribution for Laser Melting Processes

Abstract

Modelling of laser manufacturing processes involving laser melting is an extremely important activity, for controlling and optimising these processes. However, modelling of these processes is not straight-forward due to Marangoni and buoyancy convection within the melt pool. Detailed CFD models are required to accurately predict the melt pool geometry and temperature distribution. CFD modelling of melting processes requires much greater expertise and also requires longer computational time. To simplify and speed up the modelling process, many researchers have used the enhanced thermal conductivity approach to account for melt pool convection. Instead of solving the intricate Navier-Stokes equations, only the energy equation is solved by enhancing the thermal conductivity beyond the melting temperature, to predict the melt pool geometry and temperature distribution. However, researchers have used the values of enhanced thermal conductivity from the literature without any validation. Moreover it is also not established whether the enhanced thermal conductivity approach is able to predict accurately the melt pool geometry and temperature distribution. This paper presents an analysis of the enhanced thermal conductivity approach for laser melting of mild steel. The finite volume method has been used to simulate the transient effects of a moving beam for laser melting of mild steel (EN-43A). Experimental melt pool geometry has been compared with the CFD model and the enhanced thermal conductivity model.