Al-Zn-Mg-Cu合金大尺寸变截面盘类件广泛应用于航空航天、核工业等尖端领域，现有成形工艺无法兼顾高强度和低应力腐蚀敏感性的服役要求。压扭大塑性变形工艺在显著细化晶粒的同时可诱导多元合金相回溶形成过饱和固溶体，为后续时效处理充分挖掘合金性能提供可能。本研究对一种新型Al-Zn-Mg-Cu合金（12 wt.% Zn）盘类件（>Φ50mm）开展压扭成形工艺实验。基于阳极溶解和氢致破裂理论，从动力学（扩散）和电化学相关理论以及细晶强化、形变强化、时效强化机制出发，深入分析晶粒细化和多元合金相回溶对后续时效处理弥散相成分、尺寸及分布的影响，测试各特征部位（盘面及根部圆角过渡区）强度和抗应力腐蚀性能，揭示其机理，以期达到该类件高强度和良好抗应力腐蚀性能的控性目标。本研究完善了超高强铝合金抗应力腐蚀理论、拓展了压扭工艺的工业化应用，为成形高性能铝合金零件开辟新思路和研究方法，具有重要的科研价值。

Heavy-gauge discs of Al-Zn-Mg-Cu alloy with variable cross-section are widely used in aerospace and nuke industry. The present forming processes cannot satisfy the demands of both high strength and low stress-corrosion sensibility. High-pressure torsion process belonging to sever plastic deformation can remarkably refine the grains, leading to the dissolving of multi-alloy phase and the emergence of supersaturated solid solution. The process presents the possibility for improving the properties of the alloy via subsequent aging treatments. In this study, the discs (>Φ50mm) of novel Al-Zn-Mg-Cu alloy (12 wt.% Zn) are processed by high pressure torsion. Based on the theories of anodic dissolution and hydrogen-induced cracking, the influences of both grain refinement and multi-phase dissolving on the composition, size and distribution of the dispersed phase will be analyzed from the perspectives of dynamics (diffusion) , electrochemistry and the mechanism of grain-refinement, working and aging strengthening. According to these principles, the strengths and the resistances against stress-corrosion of all the distinguished sections of the disc, like the bottom and the corner at the root, are tested in order to control the over-all properties of the disc. This study will improve the theory of stress-corrosion of Al alloy, widen the industrial application of pressure torsion and develop novel ideas and methods for fabricating high-performance Al alloy parts, which has scientific value.