Eectofheattreatmentonelectrochemical behaviourofaluminiumalloyAA3005 A.Afseth a,c ,J.H.Nordlien b,1 ,G.M.Scamans c , K.Nisancioglu a, * a Department of Materials Technology and Electrochemistry, NTNU, Sem Saelands vei 6, N-7491 Trondheim, Norway b Department of Corrosion and Surface Technology, SINTEF, N-7465 Trondheim, Norway c Alcan International Ltd., Banbury Laboratory, Southam Rd., Banbury OX16 7SP, UK Received17October2000;accepted4January2001 Abstract The eect of heat treatment on the electrochemical properties of bare metal samples of aluminiumalloy3005inanacidi®edsodiumchloridesolutionwasinvestigated.Annealingat increasing temperatures in the range 150±500°C causes negative potential transients of in- creasing magnitude and longevity for samples exposed at open circuit. Electrochemical characterisationshowsthepotentialtransientstobecausedbyanincreasedanodicreaction rateoftheannealedmaterialsurfacesascomparedtothecoldrolled,hardtempersubstrate.It issuggestedthatthisincreasedanodicactivityduringshorttimeexposureofthebaremetal samples may be attributed to changes in the protective properties of the surface oxide as a result of the high temperature heat treatment. The mechanisms controlling short term elec- trochemical properties of bare metal samples may not be identical to those controlling the ®liformcorrosionsusceptibilityofcoatedproductsandacautiousapproachisrecommended when using electrochemical techniques for predicting corrosion properties. Ó 2001 Elsevier ScienceLtd.Allrightsreserved. 1. Introduction In a related paper [1] we reported that high temperature heat treatment of a cold rolled, hard temper 3005 alloy resulted in a drastic loss of ®liform corrosion www.elsevier.com/locate/corsci CorrosionScience442002)145±162 * Correspondingauthor.Tel.:+47-7359-4035;fax:+47-7359-4083. E-mail address: kemaln@chembio.ntnu.noK.Nisancioglu). 1 Presentaddress:HydroAluminiumR&DMaterialsTechnology,N-4265H avik,Norway. 0010-938X/02/$-seefrontmatter Ó 2001ElsevierScienceLtd.Allrightsreserved. PII:S0010-938X01)00024-5