Characterization of yielding of sheet metal at elevated temperatures

Abstract

Abstract In times of highest significance of process modeling and numerical simulation characterization of material properties is of special importance for components’ and tools’ dimensioning. Especially in fields of sheet metal forming the mechanical behavior of components highly differ according to real stress condition. In particular yield loci combine the information of beginning of yielding with biaxial stress conditions. Although these data are essential, they are unknown for many different sheet metals, mainly new materials used for light-weight constructions, e.g. aluminum and magnesium alloys. In this paper investigations done on a novel concept of experimental setup, which has been developed at the Chair of Manufacturing Technology (LFT) and which enables the determination of yield loci at elevated temperatures, are presented. The strategy for local heating is based on FE-calculations and verified afterwards. A 210 W-diode laser is used for the local heating of the specimens up to temperatures in the range of 300 °C. During forming process a constant temperature is guaranteed by a closed-loop temperature-control (CLTC), the homogeneous distribution of temperature in the forming zone is realized using a special optical system.