Multi-Scale Modeling of Selective Laser Melting Process

The Selective Laser Melting (SLM) process is employed in high-precision layer-by-layer Additive Manufacturing (AM) on powder bed and aims to fabricate high-quality structural components. To gain a comprehensive understanding of the process and its optimization, both modeling and simulation in conjunction with extensive experimental studies along with laser calibration studies have been attempted. Multiscale and multi-physics-based simulations have the potential to bring out a new level of insight into the complex interaction of laser melting, solidification, and defect formation in the SLM parts. SLM process encompasses various physical phenomena during the formation of metal parts, starting with laser beam incidence and heat generation, heat transfer, melt/fluid flow, phase transition, and microstructure solidification. To effectively model this Multiphysics problem, it is imperative to consider different scales and compatible boundary conditions in the simulations. In this paper, we employ a numerical model for the SLM process, leveraging multi-scale and multi-physics simulation strategies. The model will describe the transition from powder to melt and melt to microstructure solid by applying the appropriate boundary conditions at each stage in the transition process. The model also accounts for temperature-dependent material properties of Ti-6Al-4V alloy, including specific heat capacity, thermal conductivity, viscosity, etc. These effective properties are evaluated under both room temperature and elevated temperature conditions through Molecular Dynamics (MD) simulations. The basic behaviour of melting-related property variation is to be studied and the effect on the melt pool characteristics is simulated. The ultimate aim of the scheme is to plug in temperature-dependent material properties in the model and predict the temporal distribution in the melt pool. The simulation results provide a detailed explanation of the SLM process in all three phases (powder, melt, and microstructure solid).