【摘要】 为进一步提升航空铝合金厚板的组织及性能均匀性，本文研究了升、降温回归及再时效对Al-8Zn-2Mg-2Cu合金厚板厚向组织及性能均匀性的影响。结果表明，在回归加热阶段，相对于板材心层，表层预析出相的回溶程度更高，但未回溶的η′或η相尺寸相对粗大。在回归后的缓慢冷却阶段，厚板的表层和心层都存在未溶第二相的缓慢粗化和新相的二次析出。但是回归后的快冷处理可有效抑制上述两种组织演变行为。厚板的电导率以及厚向析出组织的均匀性随着回归冷却速率的降低而提高，硬度的演变规律则恰好相反。经过优化的非等温回归再时效（NRRA）处理，基于“积分回归效应”评价的厚向性能均匀程度可增加至94%。此外，Al-8Zn-2Mg-2Cu合金30 mm厚板心层的轧向抗拉强度、断裂韧性以及剥落腐蚀等级分别为619 MPa,24.7 MPa·m^1/2和EB级别。上述研究结果表明，包含升、降温处理的非等温回归再时效在保证合金综合性能的同时可有效提高板材厚向组织及性能的均匀性，更加适合厚截面高性能铝合金板材的工业化热处理。更多还原

【Abstract】 In order to improve the through-thickness homogeneity and properties of aviation aluminum alloy thick plate.The effect of heating-cooling retrogression and re-ageing on the performance of Al-8Zn-2Mg-2Cu alloy thick plate was investigated by hardness tests, electrical conductivity tests and transmission electron microscopy(TEM) observation.Results revealed that, during retrogression heating, the fine pre-precipitates in surface layer dissolve more and the undissolved η′ or η phases are more coarsened than that of center layer. During slow cooling after retrogression,precipitates continue coarsening but with a lower rate and the secondary precipitation occurs in both layers. Finer precipitates resulting from the secondary precipitation are more in surface. However, the coarsening and secondary precipitation behaviors are restrained in both layers under quick cooling condition. The electrical conductivity and through-thickness homogeneity of precipitates increases while the hardness decreases with cooling rate decreasing. After the optimized non-isothermal retrogression and re-ageing(NRRA) including air-cooling retrogression, the throughthickness homogeneity which is evaluated by integrated retrogression effects has been improved to 94%. The tensile strength, fracture toughness and exfoliation corrosion grade of Al-8Zn-2Mg-2Cu alloy plate is 619 MPa, 24.7 MPa·m1/2and EB, respectively, which indicates that the non-isothermal retrogression and re-aging(NRRA) could improve the mechanical properties and corrosion resistance with higher through-thickness homogeneity.更多还原