Researchers develop multi-scale model of sintering anisotropy in BJT stainless steel parts
Researchers from San Diego State University, California, USA, have published research in npj Advanced Manufacturing on the development of a multi-scale modelling framework to investigate anisotropy during the sintering of 316L stainless steel parts produced by Binder Jetting (BJT).
Conducted in collaboration with Eindhoven University of Technology, the Netherlands, and Clemson University, South Carolina, USA, the study combines kinetic Monte Carlo (kMC) simulations with Finite Element (FE) modelling to investigate how directional differences in material behaviour develop during sintering.
The researchers first calibrated and validated a mesoscale kMC sintering model using X-ray computed tomography (CT), discrete element modelling and optical microscopy. Interrupted thermal cycles enabled the team to examine microstructural changes at different stages of densification.
Following validation, the mesoscale model was used to determine characteristics such as strain rate and pore orientation. These were subsequently incorporated as anisotropic sintering stress inputs into a larger-scale continuum model, based on the Skorohod-Olevsky Viscous Sintering (SOVS) framework.
Developed specifically for 316L stainless steel, the continuum model accounts for several factors influencing sintering behaviour, including initial relative density, grain growth kinetics, the formation of δ-ferrite at elevated temperatures, friction and gravity.
By combining experimental imaging, tensor-based analysis and numerical simulations, the researchers were able to connect directional variations at the mesoscale with the overall sintering response of a component.
The results indicate that anisotropy evolves nonlinearly across different structural scales, highlighting the importance of accounting for microstructural behaviour when modelling sintering at the component level.
The research suggests that coupling models across different scales could support a more comprehensive understanding of anisotropic shrinkage and deformation during the sintering of binder-jetted metal components.
The paper, ‘Continuum meso-macro multiscale modeling of anisotropy during sintering of parts produced via additive manufacturing’, is available here.
