Strength and fatigue fracture behavior of Al Sn) （Al Sn)的强度和疲劳断裂行为）.pdfVIP

Trans. Nonferrous Met. Soc. China 23(2013) 2817−2825 Strength and fatigue fracture behavior of Al−Zn−Mg−Cu−Zr(−Sn) alloys Lu CHEN1 1 1 2 , An YAN , Hua-shan LIU , Xiao-qian LI 1. School of Materials Science and Engineering, Central South University, Changsha 410083, China; 2. School of Mechanical and Electric Engineering, Central South University, Changsha 410083, China Received 12 September 2012; accepted 14 January 2013 Abstract: The strength and fatigue fracture behavior of Al−Zn−Mg−Cu−Zr(−Sn) alloys were studied by performing tensile tests and fatigue crack propagation (FCP) tests. The microstructures of the experimental alloys were further analyzed using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM); phase analysis of these alloys was conducted with an X-ray diffraction (XRD). The results show that when Sn is included, growth of the recrystallization grains in the solution-treated Al−Zn−Mg−Cu−Zr alloy is obstructed, the precipitation-free zone (PFZ) of the overaged Al−Zn−Mg−Cu−Zr−Sn alloy becomes narrow, and the grain boundary precipitates are smaller. Consequently, the FCP resistance is higher. In addition, the overaged Sn-containing alloy has considerably higher tensile strength than the alloy without Sn. Key words: Al−Zn−Mg−Cu−Zr; Sn; strength; fatigue fracture behavior; microstructure the addition of trace elements. For example, the addition 1 Introduction of Zr can improve the mechanical properties of