Abstract
Cyclic temperature creep tests were carried out an AS 7075 alloy specimens were subjected to a constant load and stepwise temperature cycles in which temperature was fluctuated between 30$0^{\circ}C$ and 25$0^{\circ}C$ with three different cycle ratios. The highest frequency of cycling was 1 cycle per 10 hr and the lowest one was 1 cycle per 12 hr. From the creep experimental results with the above conditions the creep strain under cyclic temperature can be predicted easily by introd ucing the equivalent steady temperature because defined by Eq.(16), but the rupture life is 1.1 time than those of constant temperature because of effect of temperature history at tertiary creep range. Besides thlis result, the results of the creep test under cyclic temperature conditions are respectively compayiea with calculated rupture lives using the life fraction law and Eq.(18). The agreement between the obseried rupture times and calculated ones is fairly good. So creep rupture lives can be respectively predicted using life fraction law and Eq.(18).