The corrosion behaviour of machined AA7150-T651 aluminium alloy

The present work investigates the corrosion behaviour of machined AA7150-T651 aluminium alloy. It is found that machining operation introduces a near-surface deformed layer, characterized by ultrafine grains and segregation of Mg and Zn at grain boundaries, to the alloy. The near-surface deformed layer is electrochemically more active compared with the bulk alloy, therefore, is preferentially corroded during immersion in an 3.5 wt.% sodium chloride solution acidified to pH 3.2. The open circuit potential of the machined alloy shows a transient at the beginning of immersion in the solution, due to the preferential dissolution of the near-surface deformed layer.