(1. 江蘇科技大學(xué) 材料科學(xué)與工程學(xué)院, 鎮(zhèn)江 212003；
2. 中南大學(xué) 材料科學(xué)與工程學(xué)院, 長(zhǎng)沙 410083；
3. 中鋁材料應(yīng)用研究院有限公司蘇州分公司, 蘇州 215026)
摘 要: 采用力學(xué)性能測(cè)試、電導(dǎo)率測(cè)試、差示掃描量熱(DSC)分析、微觀組織觀察以及織構(gòu)分析研究預(yù)時(shí)效溫度、回歸加熱速率、再結(jié)晶及Taylor因子對(duì)回歸再時(shí)效(RRA)態(tài)7A55鋁合金厚板組織、性能及其厚向不均勻性的影響。結(jié)果表明：厚板芯部低密度和粗大的析出相(η'''' 和η)導(dǎo)致板材芯層硬度低于表層的，芯層電導(dǎo)率高于表層的。硬度和電導(dǎo)率的厚向不均勻性隨著回歸加熱速率的降低而減小，與預(yù)時(shí)效程度無(wú)關(guān)。然而，板材表層相對(duì)較高的固溶再結(jié)晶程度降低亞結(jié)構(gòu)強(qiáng)化效果，并增加再結(jié)晶織構(gòu)組分，低Taylor因子反而使RRA態(tài)厚板表層的軋向屈服強(qiáng)度低于芯層的。欠時(shí)效+慢速回歸加熱回歸再時(shí)效可以達(dá)到與傳統(tǒng)RRA類似的性能，且慢速回歸加熱更符合厚板的實(shí)際熱處理?xiàng)l件。
關(guān)鍵字: 析出相；再結(jié)晶；織構(gòu)；7A55鋁合金；厚板；不均勻性
（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
