Mechanical and micro-structural characterization of hot rolled brass foil

Abstract

To assist the large-scale production of micro parts by micro sheet metal forming processes, mechanical and microstructural behaviors of metal foils are required. In the present study, an attempt has been made to characterize these properties of 100-μm thickness as-received brass foil. Mechanical characterization of foil has been done with tensile tests, bending tests and Nakazima tests. From the tensile test analysis, it has been observed that change in strain rate has a negligible impact on flow stress. However, serrations observed in flow stress are dependent on strain rate. The Electron backscatter diffraction (EBSD) analysis of as-received and post-deformed specimens shows the concentrated rise in Kernel average misorientation, high angle grain boundaries and low angle grain boundaries in deformed specimens. The fracture morphology study shows the presence of ductile fracture in the middle region of the fracture cross-section with shear lips in the edge region. Bending experiments show that the spring-back angle increases with the increase of bending angle up to 120°. After that, with an increase in bending angle, the spring-back angle decreases. The forming limit curve (FLC) obtained from the Nakazima test was compared to FLC obtained from different prediction criteria. From this study, it was observed that the FLC obtained from Marciniak-Kuczynski (M-K) criterion showed a good prediction of FLC for brass foil. However, FLCs obtained from Swift-Hill criterion, Abspoel empirical criterion and Pamstamp's Matwizard module over estimated foil's formability.