Creep behaviour of pure aluminium at constant load and constant stress

We have carried out both a constant load and a constant stress creep test for pure aluminiums at a lower temperature, where neither diffusion nor recrystallization takes place. Whole creep curves are measured for 4N and 5N pure aluminiums at a room temperature. We discussed the difference between the constant load and the constant stress creep. The three regions, a primary, a steady state and a ternary creep, are observed under a constant load condition as well as under at a constant stress condition. Life to rupture is associated with the steady state creep, The difference of the creep damages between in a constant load creep and in a constant stress creep comes from the stress condition developed in the specimen.