Relationship between tear resistance and stress corrosion cracking

Studies on stress corrosion cracking of Al-Zn-Mg alloys (5th report)

Abstract

Tear tests, tensile tests, and stress corrosion tests of Al-Zn-Mg alloys were conducted to examine the relationship between tear resistance and stress corrosion cracking.
The results obtained were as follows:
(1) There was no complete correspondence between the sensitivity to stress corrosion cracking and unit propagation energy (UPE), But on the specimens heat-treated under the same or similar condition, there was much correspondence between them. It would probably be due to the smooth crack propagation that an Al-Zn-Mg alloy age-hardened for high strength is more brittle and more sensitive to stress corrosion cracking.
(2) The form of grain boundary in the loading direction would have great effects on the directional dependence of mechanical and stress corrosion properties. The directional dependence did not appear in specimens having equi-axial grains. Whereas, the directional dependence clearly appeared in stress corrosion tests, because the crack always propagated along the grain boundary.