ISSN 2070-2051, Protection of Metals and Physical Chemistry of Surfaces, 2015, Vol. 51, No. 2, pp. 267–274. © Pleiades Publishing, Ltd., 2015. 267 1 1. INTRODUCTION A significant attention has been given to Alumi- num-Magnesium alloys because of their low density, good strength and high corrosion resistance in several environments, including the ambient atmosphere. The reduction of the density, increase of tensile strength, weldability, and the decrease of corrosion resistance of aluminum-magnesium alloys are due to the addition of magnesium to aluminum [1–7]. These characteristics made 5083-H321 aluminium alloy a good candidate material to replace some conventional alloys in automobile and aircraft industries [1]. The aluminum-magnesium alloys are generally elaborated and used under severe conditions, and their final prop- erties depend on preliminary thermomechanical treatments that have been undergone. Several theories on pitting were narrowly con- nected to the rupture of passive film. In aluminum- magnesium alloys, pitting appears when the aggressive ions such as chlorides break or attack oxide film. The pitting starts at the defects of oxide film which gener- ally crack and appear in the site of the surface hetero- geneities [2]. However there is no study treating the effect of cold rolling and the intermediate cold rolling annealing process on the corrosion sensitivity of homogenized and stabilized 5083-H321 aluminum- magnesium alloy. Moreover the share of corrosion 1 The article is published in the original. studies of this alloy does not take into account the thermomechanical history carried out beforehand. To obtain 5083–H321 alloy with adequate physic- ochemical properties we need to have a good under- standing of phenomena and processes which occur during thermomechanical treatments for example the microstructure evolution of cold rolled aluminum- magnesium alloy [8]. The presence of different types of intermetallic particles in the alloy matrix improves mechanical properties, but carries to higher susceptibility to corro- sion. The main types of intermetallic particles in AA5083–H321 aluminum alloy are iron-manganese- chrome and magnesium-silicon rich particles: the first type is nobler and the second type is similar or less noble than the aluminum matrix [5, 6, 10–17], the last ones are responsible for localized corrosion formation on the surface of this alloy. The Al–Fe–Mn rich parti- cles are nobler than aluminum and are responsible for pitting formation surrounding alloy matrix [5, 6]. Concentrations of iron and manganese in aluminum- iron-manganese rich particles, and of magnesium and silicon in aluminum-magnesium-silicon rich particles change from a position to another in alloy AA5083 [5, 6]. The open circuit potential (OCP) of Al–Mg–Si particles for different aluminum alloys is –1.5 V/ECS just after immersion but after longer immersion times the (OCP) is up to –0.7 V/ECS [18]. The change in the composition of the MgSi phase in the course of time, after immersion in corrosive solution is due to an Thermomechanical Treatments Effect on Corrosion Behaviour of Aluminium-magnesium Alloy AA5083–H321 1 Nacer Zazi a , Jean-Paul Chopart b , and Ahcène Bouabdallah c a LMSE, Dépt de Génie Mécanique, Université Mouloud Mammeri, 15000 TiziOuzou, Algérie b LISM EA 4695 UFR SEN, BP1039, Université de Reims Champagne Ardenne, Moulin de la Housse, 51687 Reims, Cedex, France c LTSE, USTHB, BP 32 El-Alia, Babezzouar, Alger, Algérie e-mail: zazinacer@yahoo.fr Received October 11, 2013 Abstract—In this paper the process of the corrosion of the alloy 5083–H321 has been studied in 3% weight NaCl solution. We were interested in the effect of change in the physical state and chemical composition of the intermetallic particles on corrosion behavior of aluminum 5083–H321 alloy having undergone an annealing of 1h 30 min at 420°C, and having undergone the same annealing followed by various types of thermo-mechanical treatments. The results obtained show that the density of the intermetallic particles increases by 10 times and micropores are formed after the deformation by cold rolling. The distribution law of intermetallic particles changes after cold rolling. The morphology of corrosion changes also. The introduc- tion of an intermediate annealing process during cold rolling of 1h at 250°C causes a recrystallization in the alloy but does not bring change on the corrosion morphology. DOI: 10.1134/S2070205115020148 PHYSICOCHEMICAL PROBLEMS OF MATERIALS PROTECTION