The interaction between short-term heat-treatment and the formability of an Al-Mg-Si alloy regarding deep drawing processes

Research conducted in recent years has shown that heat-treatable Al-Mg-Si alloys
(6xxx) have great potential concerning the design of lightweight car bodies. Compared to
conventional deep drawing steels the field of application is limited by a lower formability. In
order to minimize the disadvantage of a lower drawability a short-term heat-treatment (SHT) can
be applied before the forming process. The SHT, conducted in selected areas on the initial blank,
leads to a local reduction of strength aiming at the decrease of critical stress during the deep
drawing process. For the successful procedure of the SHT a solid knowledge about the crucial
process parameters such as the design of the SHT layout, the SHT process time and the maximum
SHT temperature are urgently required. It also should be noted that the storage time between the
SHT and the forming processes affects the mechanical properties of the SHT area. In this paper,
the effect of diverse SHT process parameters and various storage time-frames on the major and
minor strain situation of a deep drawn part is discussed by the evaluation of the forming limit
diagram. For the purpose of achieving short heating times and a homogenous temperature
distribution a one side contact heating tool has been used for the heat treatment in this study.