CREEP-FATIGUE AND MICROMECHANISMS OF DEFORMATION IN Al-6 Mg ALLOY

摘要

The influence of low amplitude cyclic stress components on the creep of smooth cylindrical and cracked Al-6%Mg alloy specimens has been investigated. A significant increase of the creep deformation under the low amplitude cyclic loading, compared with the static creep, was found. It was found that under creep-fatigue, increases of the dislocation density, due to the decrease of the dislocation network step and formation of the secondary dislocations, takes place. This is caused by the increase of the thermal fluctuation stresses in the micro-volumes of the material as well as by activation of dislocation multiplication due to the mechanism of the cross slipping.