Concurrent Modeling of Porosity and Microstructure in Multilayer Three-Dimensional Simulations of Powder-Bed Fusion Additive Manufacturing of Inconel 718

Laser powder-bed fusion (L-PBF) additive manufacturing is a complex process whereby a laser selectively scans over layers of powder, inducing local melting and consolidation of solid metal. A key bottleneck issue which prevents L-PBF from further industrial adoption is the low repeatability of the process across different printers and powder batches. To explore and address the challenges of process repeatability, high-fidelity comprehensive physics-based modeling is desirable because it allows fast exploration of the process parameters space by simulations rather than by trial-and-error experiments. In this work, we present a complete framework which is capable of modeling defects (porosity) as well as microstructure explicitly in three dimensions and for multiple layers, effectively demonstrating explicit L-PBF of a digital cube of material at millimeter scale. The phase field method is coupled to the Lattice Boltzmann method, and the framework is used to model both the solid/liquid phase transitions as well as grain nucleation and growth. Explicit parallel scheme allows to run multiple simulations in a reasonable time and explore the role of process parameters on porosity and microstructure concurrently. After model calibration using experimentally-printed and characterized samples, the model was deployed across multiple parameter combinations. The predicted porosity and microstructure agreed well with the experiments. Our framework provides a practical demonstration of digitalization of the L-PBF process and paves the way for assessing process quality and repeatability by computer modeling and simulations.