Size effects on mechanical properties of copper thin sheet in uniaxial tensile tests

Abstract

Microforming offers a reliable method for mass production of micro parts with low cost and high precision. However, to form micro parts is more difficult than macro parts because of size effects. Uniaxial tensile tests are carried out to study the size effects on mechanical properties of copper C1100 thin sheet at room temperature on a universal testing machine. The materials are thermally treated at 873 K for 12 h in nitrogen atmosphere, and the specimens with thickness varying from 0.32 mm to 0.04 mm are manufactured by slow feeding wire cutting with initial gauge widths of 8, 4, 2, and 1 mm. In addition, a non-contact measurement device is developed to reduce the error of the contact measurement method. The results show that the size effects on mechanical property are obvious. The flow stress and elongation decrease dramatically with the decreasing specimen size. The reason for this phenomenon is also discussed by scanning electron microscope (SEM) observation and theoretical analysis.