Volume 16, Issue 1 (January 1988)
On the Analysis of Thermally Activated Tension-Tension Cyclic Deformation Behavior
The application of the transition state theory of rate processes to describe tension-tension cyclic deformation behavior was reviewed, leading to a coherent, unified theory for stress relaxation, creep, and strain and load controlled cyclic deformation. The study showed that over the stress, time, and temperature range where the rate of plastic flow can be approximated with activation over a single energy barrier, strain-controlled cyclic deformation is essentially a stress relaxation process, while creep is related to load-controlled cyclic deformation. The theory described well the deformation behavior of a near-eutectoid, zinc-aluminum alloy. The constitutive parameters determined from the analysis of stress relaxation, creep, and strain and load controlled cyclic loading experimental results were identical, leading to the conclusion that strain and load controlled cyclic deformations were different manifestations of the same basic process, depending on the control condition. Consequently, it was recommended that stress relaxation and creep can be employed to determine the constitutive parameters. By using the theory developed in this report, the cyclic deformation behavior can be predicted.