Corrosion studies on friction stir spot welded dissimilar AZ31-C27200 Cu joints

Abstract

In this investigation, corrosion studies were conducted on dissimilar friction stir spot welded AZ31 Mg-C27200 Cu joints using pitting corrosion tests. Mechanical characteristics of the joints were also evaluated. By conducting tensile testing, the tensile shear failure load value of AZ31 Mg-C27200 Cu joints were 62.36% of the value of similar AZ31 Mg – AZ31 Mg joints and 51.9% of the values of C27200 Cu– C27200 Cu joints, respectively. The joint interface hardness of the dissimilar combination such as AZ31 Mg– C27200 Cu joints were 22.03 % and 35.84% greater than the interface hardness values of similar AZ31 Mg–AZ31 Mg and C27200 Cu–C27200 Cu joints, respectively. Bend tests revealed that similar joints broke with interfacial tear and the dissimilar joints broke with nugget pullout. By conducting pitting corrosion tests on the joints, potentiodynamic polarization curves were developed. The corroded samples were subjected to microstructural evaluation using scanning electron microscopy. The variations in corrosion pit density were also identified.