Comparison of compressive creep characteristics of commercial zinc-base alloys No3 and No5

Creep tests are commonly performed by applying constant stress or load to uniaxial specimens, and creep data is obtained in the form of creep strain versus test time. This creep data is further used to determine creep related parameters, such as primary creep extension, the secondary creep rate, time to 1 % creep strain or stress to fracture at a given time. Compressive creep tests have been carried out on two commercial zinc-rich alloys No3 (Zn-4% Al-0.05% Mg). These tests were performed on a standard weighted lever arm constant load compressive creep machine using hollow cylindrical test pieces. The nominal stress range for these tests was 20 to 100 MPa. at temperatures from 70 to 160 degree centigrade. Generally, the primary creep extension was found to increase with copper content and was therefore higher in alloy No5. It was concluded from these tests that alloys No5 had a total creep deformation significantly lower than No3 under all testing condition due to its lower secondary creep rates and thus had better compressive creep strength than alloy No3. (author)