Manipulating melt pool thermofluidic transport in directed energy deposition driven by a laser intensity spatial shaping strategy

Abstract

A three-dimensional thermofluidic coupling transport model is proposed to investigate the influences of different spatial laser intensity profiles (SLIPs), including circular super-Gaussian profile (C-SGP), transverse elliptical Gaussian profile (TE-GP) and longitudinal elliptical Gaussian profile (LE-GP), on the thermofluidic transport characteristics within the melt pool. The results demonstrate that the SLIPs dramatically influence the melt pool geometries, temperature gradient (both in magnitude and direction) at the solidification interface, and fluid flow dynamics. Under the TE-GP strategy, the highest average temperature gradients are observed at the solidification interface. The LE-GP strategy yields the smallest magnitudes and narrowest variation range of the temperature gradient direction angles. The heat transport of the melt pool under the C-SGP and TE-GP strategies are jointly dominated by convective and conductive heat transfer, while those under the LE-GP strategy are dominated by convective heat transfer. Marangoni convection is strongest in the LE-GP strategy and weakest in the TE-GP strategy.