In this paper, a predictive model based on a cellular automaton (CA)-finite element (FE) method has been developed to simulate thermal history and microstructure evolution during metal solidification for a laser-based additive manufacturing process. The macroscopic FE calculation that is validated by thermocouple experiment is designed to update the temperature field and a high cooling rate. A cellular automata-finite element (CAFE) method is developed to describe grain growth in the fusion zone. In the mesoscopic CA model, heterogeneous nucleation sites, grain growth orientation and rate, epitaxial growth, remelting of preexisting grains, metal addition, grain competitive growth, and columnar to equiaxed phenomena were simulated. The developed “decentered polygon” growth algorithm is appropriate for the nonuniform temperature field. Finally, the single and multiple layer direct metal deposition (DMD) experiment is conducted to validate the characteristics of grain features in the simulation.
J. Zhang et al., "A Two-Dimensional Simulation of Grain Structure Growth within Substrate and Fusion Zone during Direct Metal Deposition," Proceedings of the 28th Annual International Solid Freeform Fabrication Symposium (2017, Austin, TX), pp. 1121-1140, University of Texas at Austin, Aug 2017.
28th Annual International Solid Freeform Fabrication Symposium -- An Additive Manufacturing Conference, SFF 2017 (2017: Aug. 7-9, Austin, TX)
Mechanical and Aerospace Engineering
Materials Science and Engineering
Intelligent Systems Center
National Aeronautics and Space Administration (NASA)
Article - Conference proceedings
09 Aug 2017