Stress corrosion cracking of a wrought Mg–Mn alloy under plane strain and plane stress conditions

Stress corrosion crack growth of a rare earth containing Mg–Mn hot rolled alloy was studied using compact tension and circumferential notch tensile specimens employing constant load in 0.1 N NaCl solution saturated with Mg(OH)2. Circumferential notch tensile specimens satisfied plane strain conditions; Log crack velocity versus stress intensity plots yielded slope of 0.5 and 1 for stage I region and threshold stress intensity of 10 and 13 MPa m1/2 for circumferential notch tensile and compact tension specimens respectively. Fractography showed transgranular features involving hydrogen in stress corrosion cracking.