An experimental study on size effects on flow stress and formability of aluminm and brass for microforming

In order to understand the characteristics of micro metal forming, tensile and bending tests were conducted on both aluminum 1100 O-temper and brass 26000(1/2) hard (H02) to investigate the influence of size effects on flow stress and formability. In this study, it has been observed that the yield strength and tensile strength decrease as T/D (thickness/average grain diameter) ratio decreases until T/D approaches one. However, as the average grain diameter is greater than thickness (T/D < 1), the yield stress increases with large deviation as the T/D ratio decreases from the results of bending test. In addition, the stretchability (formability) decreases with decrease of T/D ratio on both aluminum 1100 O-temper and Brass 26000(1/2) hard (H02). According to the research results of this study, formability and flow stress of micro forming can be expressed as functions of T/D ratio.