Relationship of RRA heat treatment with exfoliation corrosion, electrical conductivity and microstructure of AA7075 alloy

Abstract

AA7075 alloys susceptibility to exfoliation corrosion is related to distribution and size of precipitate within grain boundary, continuity within grain boundary and electrochemical behaviour. Distribution and size of precipitate in the grain also effects the conductivity of the material. The effect of different temperatures and time periods of RRA temper on exfoliation corrosion of AA7075 alloy is examined in this study. Exfoliation corrosion (EXCO) solution was prepared in accordance with ASTM G34-97 standard and the samples were kept in the solution for 48h. After the samples were processed in the solution, the susceptibility of the alloy to exfoliation corrosion, its electrical conductivity and pH values of the solution were determined using microstructure scanning. It was determined that exfoliation corrosion resistance value and electrical conductivity changed in relation to chosen temperature and time of RRA temper.