AN ATTEMPT TO DETERMINE THE EFFECT OF ENVIRONMENT ON SLOW CRACK GROWTH IN HIGHSTRENGTH ALUMINUM,

摘要

The tests performed indicate that if the phenomenon of slow crack growth due to stress corrosion is present in the two aluminum alloys, 7075-T6and 2024-T3,its effect is not clearly evident in short time tests performed on specimens having the geometry and dimensions indicated in fig. 1. By using thicker specimens which would exhibit a flat fracture surface and/or running the tests for a longer period of time the effect might be more pronounced. Of all the environments tested,the only one indicating any sign of inducing slow crack growth was the NaC1solution. With this environment the corrosion process may be associated with the removal or breaking away of a protective surface film. Furthermore,the process of stress corrosion may be aided by the presence of an observed hardened zone near the tip of the notch. (Author)