Hydrogen Embrittlement Type Stress Corrosion Cracking Behavior of Wrought Magnesium Alloy AZ31

Stress corrosion cracking (SCC) behavior of wrought magnesium alloy, AZ31, was investigated. SCC tests were performed using compact tension (CT) specimens in 3%NaCl solution under hydrogen charged conditions, where the cathodic potentials were -1.4, -2.5 and -3.0 V. According to Pourbaix diagram, the cathodic potentials of -2.5 and -3.0 V correspond to the immunity region. Under the immunity condition, hydrogen embrittlement (HE) type SCC occurred where the KIscc value was much higher than that of active path corrosion (APC) type SCC. The KIscc value decreased and the crack propagation rates, da/dt, increased with decreasing cathodic potential in the immunity region where HE type SCC occurred. At the cathodic potential of -3.0 V, da/dt was insensitive to the stress intensity factor.