Intercrystalline Corrosion and Stress Corrosion Cracking of AlZnMg Alloys

Abstract

Results of electrochemically controlled studies on the stress corrosion behavior of AlZnMg alloys in sodium chloride solutions are presented. The aim was to investigate systematically crack propagation in these alloys and its relation to metallurgical and environmental parameters. Stress corrosion cracking (SCO) is found to be a discontinuous process carried forward by anodic hydrogen embrittlement (HE). The intercrystalline nature is the result of the deformation properties of the material. Moreover, it is demonstrated that intergranular corrosion (IGC) and SCO are independent phenomena, such that metallurgical factors promoting IGC always retard the crack propagation rate.