N. Hoenen, A. E. Tekkaya
Institute of Forming Technology and Lightweight Components, TU Dortmund

In this work, the flow curves of AA6063-T4 pipe material are determined for high strains without critical heat input by performing the sheet extrusion process at sufficiently low strain rates. To determine such flow curves, the sheet extrusion process was previously presented as a suitable method. For the numerical simulation of forming processes, it is essential to know the flow stress of the used material up to high strains. To achieve plastic strains up to 1.5, a high amount of plastic work is carried out, which leads to heating of the workpiece due to dissipation. When performing forward extrusion processes at typical speeds of a hydraulic press of about 45 mm/s for a diameter reduction from 30.00 mm to 14.17 mm, this causes high temperatures in the workpiece of up to 180 °C. Especially for aluminum samples with an unstable heat treatment state, this heat input can lead to a change in the microstructure, which alters the material behavior. In addition, the analyzed sheet samples are extracted from hot extruded pipe material. To test this type of material with the sheet extrusion process, the curved samples are formed to flat specimens. The influence of this additional forming step on the flow curve is investigated as well.