Corrosion Behavior of Commercially Pure Aluminum Processed through Conventional and New ECAP Dies

This research article presents the Corrosion behavior of Equal Channel Angular Pressing (ECAP) and annealed commercial pure aluminum. To investigate experimentally, the ECAP process has been carried out up to third pass of Route A and Route C through a conventional and new dies and the results of the process showed a significant grain refinement with the high-angle of grain boundary. ECAP through a new die resulted in reduced friction, minimized recrystallization, and refined grain size. After the first pass and third pass Route C processing through the conventional die, the sample showed improvement in hardness of about 79 and 127%, respectively, and for the new die the values are found to be 83 and 151%. The corrosion studies were carried out through immersion test, salt spray analysis, and potentiodynamic polarization on annealed and ECAP-processed specimens. The immersion test showed a reduction in the corrosion rate after first pass followed by a slight increase in corrosion rate with further passes of ECAP. The results of both salt spray and polarization methods showed improved corrosion resistance with increasing the number of passes in ECAP process. The polarization curve of ECAPed specimens revealed an active region followed by a passive region while no passivating condition for the annealed specimen. Similarly, EIS plot showed diffusion layer formation with ECAPed samples. SEM analysis showed small and uniform pits with an ECAPed sample while larger pits with an annealed sample. Tafel kinetic ensured the improvement of corrosion resistance in ECAPed specimens due to UFG structure with HAGB and significant refinement in the microstructure. The specimens were processed through Route C in a new die provisioned for corrosion resistance enhancement.