Corrosion Behavior of Commercial Aluminum Alloy Processed by Equal Channel Angular Pressing

Abstract

A commercial aluminum alloy was subjected to severe plastic deformation through equal channel angular pressing (ECAP). The alloy contains a low volume fraction ofα-AlFeSi located essentially at the grain boundaries. The corrosion behavior of the ECAP’ed alloy was investigated in NaCl solution using potentiodynamic polarization and immersion tests. The effects of scan rate and NaCl concentration on the alloy susceptibility to corrosion were also studied. The results obtained were compared with those of the nonpressed alloy. ECAP leads to an intensive grain refinement accompanied by an increased dislocation density. All electrochemical tests confirm that corrosion resistance of the alloy remarkably diminished with increasing the ECAP number of passes. This is presumably due to the breakdown of theα-AlFeSi after ECAP leading to higher number of galvanic cells and enhanced dissolution of the aluminum matrix.