On the utilization of Sachs model in modeling deformation of surface grains for micro/meso scale deformation processes

Finite element method simulations have become a crucial tool in conventional metal forming process design. Microforming, which is a technology for the production of miniature parts by metal forming, is a potential process for mass production of microcomponents. However, to use finite element analysis in the design of microforming processes, material models that take into account size effects are needed. In this research, the surface layer model and the Hall-Petch relationship are combined to model materials deformation at the meso/ micro-scale. Sachs model is used to model the deformation of surface grains. To validate this newly developed materials model, scaled-down compression tests were conducted, and a good agreement between predicted and experimental flow curves was obtained. In addition, the model was used to predict the experimental results of previous research for three other materials, as well. Again, a good agreement between the predicted and experimental results was obtained. Thus, the model showed a satisfactory capability to predict flow curves for different specimen size and grain size combinations for different materials. To further verify the materials model, micro-extrusion experiments were also performed. Simulations of the micro-extrusion experiments were carried out by implementing the newly developed materials model. A reasonable agreement between the experimental and predicted micro-extrusion results was found, which validates the utilization of the newly developed material model in microforming process simulations.