Corrosion and stress corrosion cracking of ultra-high-purity Mg5Zn

This paper reports on the measurement of the corrosion rate, and the stress corrosion cracking threshold stress, for ultra-high-purity Mg–5Zn. The corrosion rate was higher than the intrinsic corrosion rate of ultra-high-purity Mg, attributed to the quality of the corrosion product film. The threshold stress for stress corrosion cracking, at an applied stress rate of 0.00016 MPa s−1, was equal to 0.7 times the yield stress in air. The ductility of the cracking indicated that the stress corrosion cracking mechanism was probably hydrogen enhanced localized plasticity.