(1. 江苏科技大学 材料科学与工程学院, 镇江 212003；
2. 中南大学 材料科学与工程学院, 长沙 410083；
3. 中铝材料应用研究院有限公司苏州分公司, 苏州 215026)
摘 要: 采用力学性能测试、电导率测试、差示扫描量热(DSC)分析、微观组织观察以及织构分析研究预时效温度、回归加热速率、再结晶及Taylor因子对回归再时效(RRA)态7A55铝合金厚板组织、性能及其厚向不均匀性的影响。结果表明：厚板芯部低密度和粗大的析出相(η'''' 和η)导致板材芯层硬度低于表层的，芯层电导率高于表层的。硬度和电导率的厚向不均匀性随着回归加热速率的降低而减小，与预时效程度无关。然而，板材表层相对较高的固溶再结晶程度降低亚结构强化效果，并增加再结晶织构组分，低Taylor因子反而使RRA态厚板表层的轧向屈服强度低于芯层的。欠时效+慢速回归加热回归再时效可以达到与传统RRA类似的性能，且慢速回归加热更符合厚板的实际热处理条件。
关键字: 析出相；再结晶；织构；7A55铝合金；厚板；不均匀性
（1. School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
3. Suzhou Branch, CHINALCO Materials Application Research Institute Co. Ltd., Suzhou 215026, China）
Abstract:Mechanical properties test, electrical conductivity, differential scanning calorimetry(DSC), microstructure observation and texture analysis were used to investigate the effect of pre-ageing temperature, retrogression heating rate, recrystallization and Taylor factor on the microstructure, properties and through-thickness inhomogeneity of 7A55-RRA treated aluminum alloy thick plates. The results show that, the precipitates (η'''' and η) with relatively lower density and coarsened size in central layer results in lower hardness value and higher electrical conductivity than those of surface layer. The inhomogeneity of hardness and electrical conductivity decrease with the retrogression rate decreasing regardless of the pre-ageing temper. However, the substructure strengthening effect decreases and the recrystallized texture increases due to the deeper degree of recrystallization after solid solution in surface layer. The lower Taylor factor in surface layer results in a lower yield strength along rolling direction. The thick plate obtains a similar properties as that of traditional RRA after under ageing + slow heating retrogression and re-ageing, and the slow heating rate much more fits the engineering reality for thick plate heat treatment.
Key words: precipitate; recrystallization; texture; 7A55 aluminum alloy; thick plate; inhomogeneity
