Multistage-aging process effect on formation of GP zones and mechanical properties in Al-Zn-Mg-Cu alloy  

多级时效处理对Al-Zn-Mg-Cu合金GP区形成及力学性能的影响（英文）

作　　者：杨荣先 刘志义[1,2] 应普友[1,2] 李俊霖[1,2] 林亮华[1,2] 曾苏民[1,2] 

机构地区：[1]中南大学有色金属材料科学与工程教育部重点实验室,长沙410083 [2]中南大学材料科学与工程学院,长沙410083

出　　处：《Transactions of Nonferrous Metals Society of China》2016年第5期1183-1190,共8页中国有色金属学报（英文版）

基　　金：Project(51171209)supported by the National Natural Science Foundation of China;Project(2012CB619506)supported by the National Basic Research Program of China;supported by the 2011 Program of Nonferrous Metals and Materials,China

摘　　要：The tensile properties and fatigue behavior of an Al-Zn-Mg-Cu alloy were investigated by performing tensile tests and fatigue crack propagation （FCP） tests. The tensile results show that lower aging temperature modified retrogression and re-aging （RRA） process enhances the elongation, but reduces the strength of the alloy, as compared to conventional RRA process which employs peak aging temperature. Both ductility and strength, however, are increased by employing a natural aging prior to re-aging based on the former modified RRA process. Fatigue test results show that both routes reduce FCP rate. Especially, the lower re-aging temperature modified RRA process obtains the lowest FCP rate. Natural aging treatment could enhance the nucleation rate of GP zones. A large amount of GP zones could be cut by dislocations, which is responsible for the highest tensile strength and elongation, as well as lower FCP rate.通过拉伸性能和疲劳裂纹扩展试验研究Al-Zn-Mg-Cu合金的拉伸性能和疲劳性能。拉伸试验结果显示,与利用峰时效温度的传统回归再时效(RRA)相比,较低时效温度的RRA处理能够提高合金的伸长率,但是降低了合金的强度。但是,在前面改良的RRA处理基础上,在再时效之前增加自然时效,可以同时提高合金的强度和塑性。疲劳测试结果显示,两条改良的工艺路线都可以降低疲劳裂纹扩展速率。尤其是采用较低再时效温度改良的RRA工艺获得最低的疲劳扩展速率。自然时效处理提高了GP区的形核速率。大量的GP区都能够被位错切割。因此该状态合金拥有最高的强度和伸长率,以及较低的疲劳裂纹扩展速率。

关 键 词：Al-Zn-Mg-Cu alloy multistage-aging process tensile properties fatigue property GP zone 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG156.92[金属学及工艺—金属材料]