Effect of grain size on fine micro-blanking for Inconel 718 foil

Abstract

The influence of grain size on low-strength metal and alloy foils has been extensively discussed as an important factor in the “size effect” of micro-forming. It is relatively difficult to observe these effects in high-strength metal and alloy foils for micro-blanking. Blanking tests and simulations were conducted on Inconel 718 foils with a thickness of 100 μm to investigate the effects of different grain sizes on the fine micro-blanking process and results. A micro-blanking surface with full burnish depth and no fracture zone can be obtained using our fine blanking technique. Grain growth reduces burr height but increases rollover depth. The fine blanking empirical formula cannot be applied to calculate the maximum micro-blanking force for fine micro-blanking technology when grain sizes differ. A revised empirical formula was established for fine micro-blanking force. A size effect model for fine micro-blanking was established based on the grain deformation mechanism, which reflects the enhancement in shear sensitivity with grain growth. We established an advanced, effective method for Inconel 718 foil micro-blanking. This work may contribute to the optimal selection of forming force for fine micro-blanking applications.