A major challenge in processing 7xxx series aluminum alloys is their limited formability at room temperature. In this paper, for the alloys EN AW-7020 and EN AW-7075, various variants of the W-temper forming process are investigated. For both alloys, a good cold formability and a high strength after aging can be achieved. The effects of solution heat treatment or retrogression temperature and holding time, as well as the influence of plastic deformation after quenching, were studied. For various combinations of process parameters, the formability of the as-quenched materials and the hardening performance during artificial aging were examined. For this, hardness measurements and differential scanning calorimetry (DSC) experiments were performed along the entire process chain, to reveal the development of the hardening precipitates. After solution heat treatment and quenching, the yield stress and hardness of both investigated alloys were drastically reduced in comparison to their initial T6 states, while the ductility was significantly increased. By a subsequent simple artificial aging treatment, the same hardness as in the T6 state could be restored. It was observed that plastic deformation immediately after quenching significantly decreased the artificial aging time to achieve the peak hardness. Besides the conventional solution heat treatment process, an alternative retrogression and re-aging procedure was identified for the alloy EN AW-7020. While the heat treatment temperature can be reduced as compared to the conventional solution heat treatment, the formability and hardenability are equally good. In contrast, no such alternative process could be identified for the alloy EN AW-7075.

中文翻译：

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为7xxx系列铝合金的W型回火成形优化热处理参数

加工7xxx系列铝合金的主要挑战是其在室温下有限的可成型性。在本文中，针对合金EN AW-7020和EN AW-7075，研究了W型回火成形工艺的各种变体。对于这两种合金，可以实现良好的冷成形性和时效后的高强度。研究了固溶热处理或回火温度和保温时间的影响，以及淬火后塑性变形的影响。对于工艺参数的各种组合，检查了淬火后材料的可成型性和人工时效过程中的硬化性能。为此，在整个工艺链中进行了硬度测量和差示扫描量热（DSC）实验，以揭示硬化沉淀物的形成。经过固溶热处理和淬火后，与最初的T6状态相比，两种研究合金的屈服应力和硬度都大大降低，而塑性却显着提高。通过随后的简单的人工时效处理，可以恢复与T6状态相同的硬度。观察到，淬火后立即发生的塑性变形显着减少了人工时效时间，从而达到了峰值硬度。除了常规的固溶热处理工艺外，还确定了合金EN AW-7020的替代回火和再时效程序。与传统的固溶热处理相比，虽然可以降低热处理温度，但是可成形性和淬透性同样良好。相反，