Thermomechanical treatment is often conducted to improve the formability and performance of high-strength aluminum alloys simultaneously. This paper presents an improved creep-age forming (CAF) processing technology that combines thermomechanical pretreatment and CAF. The proposed processing technique is expected to enhance the forming efficiency and comprehensive properties of Al–Zn–Mg–Cu alloys subjected to CAF. Creep-aging behavior and properties of the 7150 aluminum alloy undergoing retrogression and re-aging (RRA) with 3 % pre-strain treatment was experimentally investigated in this study. Results obtained reveal greater creep deformation in thermomechanically pretreated samples than in those pretreated using RRA or 3 % pre-strain exclusively. Mechanical properties, electrical conductivity, and exfoliation corrosion of creep-aged samples with thermomechanical pretreatment were closely match those of the traditional RRA-treated sample. Microstructure observation discovered η₂ phase in the creep-aged RRA pretreated sample in addition to conventional GP / η’ phase, η phase and coarse and discrete grain-boundary precipitates. Low concentration of solutes in matrix in RRA pretreated sample impeded dislocation motion less and pre-strain-induced dislocations increased the creep strain significantly. Moreover, hardening effect of η2 phase and dislocation hardening compensated the strength loss due to precipitation coarsening. The proposed thermomechanical pretreatment process provides an appropriate initial temper for CAF of Al–Zn–Mg–Cu alloys, thereby improving the creep formability and comprehensive properties remarkably. The findings of this study could aid in the development of CAF technology for Al–Zn–Mg–Cu alloys, especially in terms of manufacturing aviation components.

通常进行热机械处理以同时改善高强度铝合金的可成形性和性能。本文提出了一种结合了热机械预处理和CAF的改进的蠕变成形（CAF）处理技术。所提出的加工技术有望提高经受CAF的Al-Zn-Mg-Cu合金的成形效率和综合性能。在本研究中，通过实验研究了经过3％预应变处理的7150铝合金的回归和时效（RRA）蠕变时效行为和性能。获得的结果表明，与仅使用RRA或3％预应变进行预处理的样品相比，热机械预处理的样品具有更大的蠕变变形。机械性能，电导率，热机械预处理对蠕变时效样品的剥落腐蚀和剥落腐蚀与传统RRA处理的样品非常接近。显微组织观察发现η₂在蠕变老年RRA相除了常规的GP /η”相，η相和粗和离散的晶界析出物的预处理样品。RRA预处理的样品中基质中溶质的浓度低，阻碍了位错运动，并且应变前诱导的位错显着增加了蠕变应变。而且，η2相的硬化效果和位错硬化补偿了由于析出粗化引起的强度损失。所提出的热机械预处理工艺为Al–Zn–Mg–Cu合金的CAF提供了适当的初始回火，从而显着改善了蠕变成形性和综合性能。这项研究的发现可以帮助开发Al-Zn-Mg-Cu合金的CAF技术，特别是在制造航空零件方面。