Experimental studies and numerical modeling of the specimen and grain size effects on the flow stress of sheet metal in microforming

- Interactive effect of grain and specimen sizes on deformation behavior is studied.
- The volume fraction of grain boundary changes with the specimen and grain sizes.
- The flow stress decreases linearly with the ratio of specimen to grain sizes.
- Flow stress decreases with the increasing volume fraction of surface grains.
- Methodology to identify the surface and internal grain properties is proposed.