时效制度对Al–Zn-Mg合金组织和抗应力腐蚀性能的影响  

Effect of aging on the microstructure and stress corrosion resistance of Al–Zn-Mg alloy

作　　者：叶凌英[1,2,3] 杨汶卿 唐建国 刘胜胆[1,2,3] 邓运来 张新明[1,2,3] YE Ling-ying;YANG Wen-qing;TANG Jian-guo;LIU Sheng-dan;DENG Yun-lai;ZHANG Xin-ming(School of Materials Science and Engineering,Central South University,Changsha 410083,China;Key Laboratory of Nonferrous MetalMaterials Science and Engineering(Ministry of Education),Central South University,Changsha 410083,China;Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center,Central South University,Changsha 410083,China)

机构地区：[1]中南大学材料科学与工程学院,长沙410083 [2]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 [3]中南大学有色金属先进结构材料与制造协同创新中心,长沙410083

出　　处：《工程科学学报》2019年第12期1575-1582,共8页Chinese Journal of Engineering

基　　金：国家重点基础研究发展规划资助项目（2016YFB0300901）

摘　　要：采用慢应变速率拉伸应力腐蚀、室温拉伸、透射电镜等检测方法,研究传统T5、T73时效处理,以及新型T5I4、T5I6断续时效处理对Al-Zn‒Mg合金微观组织、室温拉伸性能及抗应力腐蚀性能的影响.结果表明:断续时效T5I4处理后材料抗拉强度为400.0 MPa,明显高于传统T5及T73态样品,但材料抗应力腐蚀性能变差,应力腐蚀敏感系数为5.7%;而经断续时效T5I6处理后,材料的抗拉强度为408.5 MPa,较T5I4态相比有所提升,与此同时抗应力腐蚀性能也得到明显改善,应力腐蚀敏感系数为3.2%,该值明显小于T5I4及T5态;T5I4态晶内析出相平均粒径为2.0 nm,体积分数为8.8%,均明显小于其他3种时效制度,其晶界析出相为细小且连续分布的点状析出相;而经T5I6时效处理后晶内析出相体积分数为24.6%,明显大于其他3种时效制度,晶内析出相平均粒径(4.1 nm)较T5I4态有所增大,但依然小于T5、T73态,其晶界处析出相与T5I4态相比更加粗大,呈断续分布形貌.Controlling the balance between mechanical properties and stress corrosion resistance of Al–Zn‒Mg alloys by aging tempers has long been an active focal point of research.Traditional peak-age can improve the mechanical properties,but the continuous precipitate at the grain boundary reduces the stress corrosion resistance of the alloy.While alloys in over-aged(T73)condition show good resistance to stress corrosion,their mechanical properties will drop significantly.In this paper,tensile properties,resistances to stress corrosion,and microstructures of the Al–Zn‒Mg alloy,in interrupted aged(T5I4,T5I6)and traditional(T5,T73)tempers,were studied using a tensile test,a slow strain rate tensile test,and transmission electron microscopy.Results reveal that the tensile strength of T5I4 temper is 400.0 MPa,higher than that of T5,T73 tempers,while the stress corrosion resistance is clearly compromised,with index of slow strain rate testing,ISSRT,of 5.7%,significantly larger than that of the other three aging treatments.The tensile strength of the T5I6 temper increases to 408.5 MPa,and the stress corrosion resistance is also improved,to ISSRT=3.2%,significantly lower than that of T5 and T5I4 tempers.Volume fraction(8.8%)and average particle diameter(2.0 nm)of intragranular precipitates of T5I4 temper has the minimum value among the four aging treatments,and there are large numbers of fine precipitates distributed continuously at grain boundaries.In the T5I6 temper,the number of intragranular precipitates increase significantly,and the volume fraction of intragranular precipitates is 24.6%,larger than that of the other three aging treatments.In addition,the average particle diameter(4.1 nm)of the intragranular precipitates of the T5I6 temper is larger than that of the T5I4 temper,but is still smaller than that of the T5 and T73 tempers.Precipitates at the grain boundaries of the T5I6 temper are unevenly distributed,and significantly larger than those of the T5I4 temper.

关 键 词：Al–Zn‒Mg合金 断续时效 抗应力腐蚀 微观组织 室温拉伸 

分 类 号：TG146.2[一般工业技术—材料科学与工程]