Corrosion Behavior of Ultra Fine Grain Copper Produced by Accumulative Roll Bonding Process

In this study the effect of microstructure changes on the corrosion behavior of pure tough pitch copper in 3.5 % NaCl solution with pH = 5.5 at ambient temperature was studied. Accumulative roll bonding process as severe plastic deformation was applied up to 8 cycles to produce the ultrafine grain copper. For corrosion resistance investigations, the polarization and electrochemical impedance spectroscopy was used. Corrosion morphologies analyzed by FE-SEM microscopy after polarization and immersion tests. Results show the minimum corrosion resistance for cycle 2 and maximum corrosion resistance for cycle 8. Corrosion rate of copper decreased after it was rolled for forth time. The corrosion degradation in cycle 8 was uniform and it was intergranular for sample of cycle 2 and unrolled counterpart. The higher corrosion rate in cycle 2 was attributed to unstable microstructure and the uniform corrosion of cycle 8 was due to ultra fine grain formation.