Study of Efficient Regimes of Selective Laser Melting Based on Implicit Matrix-Free Numerical Schemes

A new approach for the numerical modeling of the selective laser melting process and optimizing its technological parameters is presented. To simulate the process of the selective laser melting (SLM), a three-dimensional nonstationary nonlinear heat equation for a multiphase system in the enthalpy formulation is solved. An implicit difference scheme is used in the developed matrix-free implementation for efficient numerical computations. The modeling results determine the geometric parameters of a system of overlapping tracks—traces of laser-assisted fusion of powder material. The influence of laser melting parameters (power, speed, and laser beam step) on the microstructural features of quasi-regular material defects, represented by regions of multiple “undermelted” or “over-melted” defects, is studied. Previously, using the developed multimode fatigue failure model, the decisive influence of the formed structure of “undermelted” defects on the catastrophic drop in fatigue strength and durability under high-frequency loading of SLM-printed samples was demonstrated. To identify this most unfavorable mode, systematic calculations were performed to construct a relationship between the critical laser beam step parameter, its power, and beam speed. The results obtained allow us to estimate the permissible range of SLM parameters for maintaining acceptable fatigue strength and durability.