Multi-track, Multi-layer Dendrite Growth and Solid Phase Transformation Analysis during Additive Manufacturing of H13 Tool Steel Using a Combined Hybrid Cellular Automata/Phase Field and Solid-state Phase Prediction Models

Using an efficient hybrid Cellular Automata/Phase Field (CA-PF) dendrite growth modeling in combination with a solid phase transformation model, microstructure evolution and solid-phase transformation were predicted during laser direct deposition (LDD) of H13 tool steel powder across multiple tracks and layers. Temperature and surface geometry data were provided by a comprehensive physics-based laser deposition model. The computational efficiency of the CA-PF model allows for simulating domains large enough to capture dendrite growth across an entire molten pool and into neighboring LDD tracks. The microstructure of the target track is strongly affected by heat from neighboring tracks including re-melting and re-solidification, and martensite tempering. Dendrite size and growth direction across the entire fusion zone, as well as predicted hardness values, are found to be in good agreement with experimental results.