Abstract—The material for experiments was an aluminum alloys series 7xxx obtained by thermo-mechanical processing. We studied the influence of different artificial aging parameters on mechanical characteristic and corrosion of Al-Zn-Mg-Cu-alloy. The Al alloys was solution treated at 475±5 o C for 60 minutes, quenched in water 40-60 o C and artificial aging at 120, 150, 180, 210 o C at different time of aging (60, respectively 300, 540, 720 minutes). After heat treatment the obtained alloys were corroded in solution of 53g NaCl + 1000 ml distilled water and boiled in these solutions for 24 hours. After corrosion test, samples were prepared for optical microstructural analyzing and mechanical tested. We observed that the best corrosion behavior has the sample aged at 180 o C /12 hours, when coalescence occurs and the weakest corrosion behavior has the sample aged at 180 o C /1 hour (better behavior in comparison with the sample aged at 210 o C). At 150 o C the maximum hardness is higher, while the decreases of hardness in time are lower and corrosion behavior is better for all samples. Keywords—7xxx aluminum alloys, Artificial ageing, Micro- structure analysis, General corrosion I. INTRODUCTION HE wide range use of aluminum and aluminum alloys in the transportation industry (aircraft, automotive industry, etc.) is based on superior mechanical characteristics of these alloys, low specific weight and corrosion resistance. Superior mechanical characteristics and optimal chemical characteristics of aluminum alloys are obtained due to the possible application of structural hardening treatments and compositional modifications. The 7xxx series alloys are very strong heat treatable alloys and they can be strengthened through heat treatment (precipitation hardening) based on the combination of zinc (mostly between 4–6 wt %) and magnesium (range 1–3 wt %) [1,2]. The high strength Al-Zn- Mg-(Cu, Zr) system or 7xxx series alloys is a highly complex one and are greatly determined by the main phases in the alloys, i.e. Guiner-Preston zones, η′, η, T, S, Mg 2 Si and Fe rich intermetallic phases [3-6]. In commercial 7xxx alloys, only η (MgZn 2 ; (Al, Zn) 2 Mg ), T (Mg 3 Zn 3 Al 2 ; Al 6 Mg 11 Zn 11 ) and S (Al 2 CuMg) phases could appear in his structure [5-8]. Fig 1 The Al-Zn equilibrium phase diagram [9] According to the binary equilibrium diagram of Al-Zn (Fig.1) [9], because of existence of solvus solubility, at temperature decreasing, decrease the solubility of solid solution. The decreased solubility of solid solution leads to its saturation and the material becomes thermodynamically unstable and therefore will tend to decompose into two new phases. Since the material is put into solution and then rapidly cooled (quenching) at a temperature below the solvus curve, the alloy matrix remains in the metastable state of supersaturated solid solution. At reheating of material at moderate temperatures, below the solvus line, at ageing, from solid solution occurs precipitation of a metastable phase in alloy matrix. The phases which appear in matrix at the precipitation process in 7xxx series alloys deduced from X-ray and electron microscope investigations consisted in supersolid solid solution → spherical Guiner Preston (GP) Zones → Internally ordered GP zones→ intermediate M (MgZn 2 ) phase →Stable T (Al 2 Mg 3 Zn 3 ) phase [10]. Heat treatment process parameters such as aging temperature and aging time operate differently according to different conditions. Technical purity aluminum, Al-Mg alloys, Al-Mg-Si alloys with Mg 2 Si as intergranular precipitate and other aluminum alloys where is not observed or there are small potential differences between the matrix and intergranular precipitates, are generally not susceptible to severe intergranular corrosion [11]-[15]. Experimental researches on the corrosion behavior and microstructural aspects of heat treated Al-Zn-Mg-Cu alloys Maria-Cristiana Enescu, Ileana-Nicoleta Popescu, Raluca Zamfir, Alina Molagic, Vasile Bratu T Issue 4, Volume 4, 2010 122 INTERNATIONAL JOURNAL of ENERGY and ENVIRONMENT