Crystallography of Stress Corrosion Cracking in Pure Magnesium

A crystallographic characterization study has been made of the transgranular stress corrosion cracking in pure Mg tested at room temperature in aqueous NaCl-K2CrO4. Selected area electron channeling and photogrammetry were used to determine the cracking orientation. The fracture surfaces consisted of flat parallel {22¯03} facets approximately 10° off the {11¯01}. These facets are separated by steps also following {22¯03} planes. The fractographic evidence shows that cracking occurs by cleavage. The crystallographic characteristics and the low energy nature of the fracture surfaces are discussed in relation to compatible stress corrosion cracking models.