Inverse Approach to the Forming Simulation of Tailored Heat Treated Blanks

Compared with the conventional manufacturing of aluminum sheet metal, the forming of so called Tailored Heat Treated Blanks (THTB) enables the production of complex aluminum sheet metal parts [1], [2]. The reasons for the lower forming behavior of aluminum alloys are well founded in the material properties. Especially smaller values for uniform elongation (< 30 %) and vertical anisotropy (< 1) limit the attainable forming result. Within the THTB process sequence a local heat treatment lowers the initial yield stress of the aluminum sheet and the altered material condition is preserved for about six hours. In this time-frame a cold forming operation has to be carried out. While using the precipitation hardenable aluminum alloys from the AA6xxx-series, the local heat treatment gives the possibility of a specific strength pattern adapted to the forming operation, thus reducing necessary process forces. Different heat sources can be used for the heat treatment, e.g. a Nd:YAG-Laser [3] or heat conduction [4].