A study on the SCC susceptibility of friction stir welded AZ31 Mg sheet

Abstract

In this study, the stress corrosion cracking (SCC) behavior of friction stir welded (FSW) AZ31 Mg alloy was examined using slow strain rate tensile (SSRT) test method. Electrochemical impedance spectroscopy (EIS) and salt spray tests were carried to understand the general corrosion behavior. The FSW AZ31 Mg samples exhibited higher SCC susceptibility than the base material during SSRT in corrosive environment. The failure of the FSW AZ31 Mg samples occurred in the stir zone (SZ) when tested in corrosive environment, in contrast to the failure in the thermo mechanically affected zone (TMAZ) observed in tests in air. However, the EIS and salt spray test results showed a higher general corrosion resistance of the SZ than the base material. The study suggests that hydrogen assisted cracking could be a reason for the higher SCC susceptibility of FSW AZ31 Mg samples than the base material.