Computer Simulation of Hydrodynamic and Thermal Processes in DLD Technology

Abstract

This article deals with the theoretical issues of the formation of a melt pool during the process of direct laser deposition. The shape and size of the pool depends on many parameters, such as the speed and power of the process, the optical and physical properties of the material, and the powder consumption. On the other hand, the influence of the physical processes occurring in the material on one another is significant: for instance, the heating of the powder and the substrate by laser radiation, or the formation of the free surface of the melt, taking into account the Marangoni effect. This paper proposes a model for determining the size of the melt bath, developed in a one-dimensional approximation of the boundary layer flow. The dimensions and profile of the surface and bottom of the melt pool are obtained by solving the problem of convective heat transfer. The influence of the residual temperature from the previous track, as well as the heat from the heated powder of the gas–powder jet, taking into account its spatial distribution, is considered. The simulation of the size and shape of the melt pool, as well as its free surface profile for different alloys, is performed with 316 L steel, Inconel 718 nickel alloy, and VT6 titanium alloy

Laser Remelting Process Simulation and Optimization for Additive Manufacturing of Nickel-Based Super Alloys

“…The melt pool front experiences a larger temperature gradient than the backside, which leads to an elliptical melt pool shape. This finding is in agreement with the results of Turichin et al [ 19 ], who modeled a laser welding process for DMD with and without powder addition for three materials (Inconel 718, stainless steel 316 L, and a titanium alloy) and found elongated melt pool geometries for all conditions. Hence, the results confirm that laser welding at moderate to high scanning speeds typically leads to elliptical melt pool shapes.…”

Special Issue: Materials, Design and Process Development for Additive Manufacturing

“…Computer modeling expands the understanding of processes occurring during manufacturing and provides information for further improvement of technology. In the article [ 2 ], a model has been proposed for the estimation of parameters of a melt pool in laser metal deposition technology (powder-based directed energy deposition process), and the influence of the residual temperature from the previous deposited layers as well as the temperature of the heated powder in the gas–powder jet, taking into account its spatial distribution are considered. Modeling of the size and shape of the melt pool, as well as the profile of its surface, was performed for various alloys: 316 L stainless steel, Inconel 718 nickel alloy and Ti-6Al-4V titanium alloy.…”