Computer simulation of microstructure development in powder-bed additive manufacturing with crystallographic texture

Parts produced via laser powder-bed fusion additive manufacturing exhibit complex microstructures that depend on processing variables and often vary widely in crystallographic texture and grain morphology. The need to understand, predict, and control these microstructural variations motivates the development of modeling tools capable of accurately predicting LPBF microstructures. Monte Carlo (MC) Potts models have been employed to successfully model the formation of grain structures in additively manufactured parts but have lacked the ability to simulate crystallographic texture. We present an extension of the MC Potts model that assigns an orientation to each grain and penalizes growth of solid into the fusion zone based on proximity of the nearest 100 crystal direction to the local temperature gradient direction. This allows for crystallographically selective growth to drive texture formation during the development of the solidification microstructure in each melt track. LPBF builds of alloy 718 with a unidirectional scan pattern provided microstructures with substantial variations in grain size, grain morphology, and texture. These distinctive albeit atypical microstructures were used to validate the simulation method, i.e. good agreement was obtained between the simulated and experimental grain shapes and textures.

Automated summary

In order to drive crystallographic formation during the development of solidification microstructure in LPBF materials, researchers proposed an improved MC Potts model that can assign orientations to each grain and selectively control growth based on proximity to crystal directions. Validation with LPBF builds of alloy 718 showed good agreement between simulated and experimental grain shapes and textures, confirming the accuracy of the simulation method.