The high-strength aluminium alloys EN AW-6082 and -7075 possess great light-weight construction potential due to their high specific strength. However, their range of applications is limited by the low cold formability and high springback in the ultra-high-strength T6 state. To extend formability, either preconditioned semi-finished products, requiring a subsequent heat treatment or temperature-supported process routes such as warm forming or hot forming die quenching (HFQ) are used. If the forming degrees achievable with these methods are not sufficient, multi-stage forming is required. The forming degrees are limited by strain hardening in case of a cold forming operation of preconditioned semi-finished products and by heat transfer between the component and the tool parts in case of temperature-supported process routes. In order to reduce or even eliminate the cooling of the component in the subsequent forming stages, a four-stage forming tool with temperature-controlled active parts was developed and its influences investigated in more detail. The paper will demonstrate how precise temperature control of the tool components contributes to an extension of the formability. In addition, reproducible and robust process conditions can be guaranteed throughout the entire process chain.

Mittels einer Vorkonditionierung in den W-Temper- (W-) oder weichgeglühten (O-) Zustand kann die Umformbarkeit der hochfesten Aluminiumlegierungen EN AW-6082 und -7075 signifikant gesteigert werden. Die so realisierbare Kaltumformung sorgt vor allem bei mehrstufigen Anwendungen für eine vereinfachte Prozessführung gegenüber temperaturunterstützten Prozessrouten, führt jedoch zu ausgeprägten Verfestigungseffekten. Deren Klassifizierung und Quantifizierung sind Inhalt dieses Beitrags.   By means of preconditioning to the W-temper- (W-) or soft-annealed (O-) state, the formability of the high-strength aluminium alloys EN AW-6082 and -7075 can be increased significantly. These preconditioned alloys enable cold forming, which ensures simplified process control compared to temperature-supported process routes, especially in multi-stage applications. In return, this leads to pronounced strain-hardening effects. Their classification and quantification are the subject of this article.

Aufgrund ihrer geringen Kaltumformbarkeit werden hochfeste Aluminiumlegierungen in temperaturunterstützten Prozessrouten umgeformt. Bei mehrstufigen Prozessen führt dies zu komplexen und störanfälligen Prozessfolgen. Eine Umformung im W-Temper-Zustand vereinfacht die Temperaturführung und steigert die Robustheit. Die hierbei möglichen Prozessführungen sowie die Einflüsse der relevanten Prozessparameter (Zeit und Abschreckmethode) sind Inhalt dieses Beitrags.   Due to their low cold formability, high-strength aluminum alloys are formed in temperature-supported process routes. This leads to complex and failure-prone process sequences in multi-stage processes. Forming in the W-Temper state simplifies temperature control and increases robustness. This paper deals with the possible process control as well as the influences of the relevant process parameters (time and quenching method).

The high-strength aluminium alloys EN AW-6082 and -7075 are characterized by low density and high strength but also limited cold formability and pronounced springback behaviour in the ultra-high-strength T6 state. In order to exploit their lightweight design potential, temperature-supported process routes such as warm or hot forming are applied. Alternatively, there is the possibility of cold forming preconditioned semi-finished products at the expense of the initial material properties. Common to all variants are complex interrelationships due to linked plant periphery resulting from up- and downstream heat treatments. In addition, occurring heat transfers in temperature-supported process routes or strain hardening effects during cold forming lead to reduced formability. Especially for multi-stage forming processes, as they are required for complex components, the above-mentioned process routes reach their limits. The different requirements of the four single-stages (deep drawing, blanking, collar drawing and upsetting) for the production of a demonstrator geometry with adapted wall thicknesses make a new type of temperature control necessary. This paper shows that the combination of temperature-supported and multi-stage forming contributes to a significant increase in formability. The temperature-controlled forming tool used for this purpose enables an inline heating of the components during the process, so that an industrially feasible and economical overall process chain for the fabrication of the demonstrator geometry out of those alloys is convertible.