Abstract
Aging effects on the stress corrosion cracking of Cu-4%Ti alloy were investigated, where aging temperature was fixed at 450°C. Specimens were subjected to a uniaxial tensile load in aqueous ammonia containing cupric complex ions. We obtained the following results.
Stress corrosion lives were strongly dependent on the aging time and the minimum life was obtained in the specimen aged about 1 hr. From the microscopic observation only intergranular cracks were found in as-quenched specimens, but inter- and transgranular cracks were found in aged specimens. Stress corrosion lives, in all specimens, were predominantly controlled by propagation of intergranular cracks.
For the dislocation structures after tensile deformation, planar arrays were not observed in the as-quenched specimen, but in the aged specimens. These planar arrays of dislocations could be assigned to the high susceptibility of the aged specimens, but they could not account for the differences of stress corrosion lives with aging time. Therefore, the high stress corrosion susceptibility of this alloy seems to be related to the modulated structure formed during the aging process.
Discontinuous pricipitates in the aged specimens acted as arresters against the propagation of stress corrosion cracks.
