Stress Corrosion Cracking Behavior of an AlLiCuMg Alloy

Al-2.4% Li-1.2% Cu-0.6% Mg-0.1% Zr alloy plates were aged to various temper conditions and subjected to short-transverse stress corrosion tests in laboratory and marine atmosphere environments, using both smooth and precracked specimens. Although stress corrosion resistance as measured with smooth specimens was poor in all tempers, it improved with increased aging time. Threshold stress intensities (⁠K_ISCC⁠) estimated from precracked specimens ranged from 8.5 to 11 MPa m⁠, decreasing with increasing aging time. The relative roles of toughness variations, crack initiation vs crack propagation resistance, and crack morphology effects on the apparent difference in response of the two specimen types to aging remain unclear.