Corrosion Behavior of AA7075-T73 Aluminum Alloy During Machining of Aeronautical Components

Abstract

Corrosion of AA7075-T73 aluminum alloy during machining process was studied. An experimental device was proposed in order to simulate machining procedure. A design of experiments-DOE was used in order to evaluate what process parameter is significant. Some electrochemical tests based on open-circuit potential vs time measurements and potentiodynamic polarization were performed in machining fluid of low and high chloride concentrations. Results from DOE showed that the chloride concentration in machining fluid and the presence or not of a zinc coating on the bench vice jaw material in the machining system, along with the interaction between these both factors are significant. OCP results showed oxide growth with time in low and high chloride concentration machining fluid. Passivity breakdown was only observed in high chloride concentration machining fluid. Best fitted parameters were applied to a large scale aeronautical manufacturing company, achieving 95 % reduction in corrosion appearance on the manufactured parts.

The Influence of the Over-Aging in 7075 Aluminium Alloy Plates on the Corrosion Behaviour

“…The influence of alloying elements and impurities on the corrosion of 7xxx series aluminium alloys was studied in several works [2][3][4][5]. Due to the anodic behaviour in relation to the surrounding aluminium matrix of the intermetallic compounds containing Zn and Mg [6,7], and on the other hand to the cathodic behaviour determined by the intermetallic particles containing Fe, Cu and Mn, severe galvanic micro-coupling corrosion results, making in finally, the predisposition to the corrosion of the 7xxx series aluminium alloys [8].…”