Abstract
Accumulative Roll-Bonding (ARB) is one of the novel Severe Plastic Deformation (SPD) techniques that was developed in recent years and successfully applied to introduce a nanocrystalline structure in various metals. In this paper, as-received sheets of 5052 aluminum alloy were initially annealed before conducting ARB process up to five passes. Pitting corrosion behavior of AA5052 in 3.5%wt NaCl solution was investigated before and after ARB process. Open Circuit Potential (OCP) of electrodes was recorded and Potentiodynamic Polarization (PP) and Cyclic Voltametery (CV) tests were carried out. It is found that, in comparison with as-received specimens, breakdown and repassivation potentials (Ebd and Erp, respectively) of annealed specimens were significantly higher which indicated that pitting corrosion resistance was enhanced due to anneal heat treatment. On the other hand, ARB process had a destructive effect on the pitting corrosion resistance of specimens and Ebd and Erp values shifted slightly toward negative direction after each pass. However, these values were still above that obtained for as-received condition. SEM and OM microscopy observations of sample surfaces after 3 weeks immersion test confirmed the electrochemical examination results.
Keywords
)