Interpretation of the Recovery/Work-Hardening Model of Creep

Abstract

A simple quantitative description of the recovery work-hardening theory of creep is presented in terms of the cooperative relationship between dislocation glide and recovery. This study involves the use of a mathematical model that simulates the relationship between the creep rate and internal and applied stresses. Of particular interest is the transient strain/time behaviour that accompanies a sudden stress change. It is shown that the accepted techniques for experimentally determining the strain-hardening rate, h, and the recovery rate, r, during creep are generally invalid because applied stresses and not internal stresses are treated. This discrepancy between the measured and actual values of r and h exists when the internal stress and applied stress are significantly different. A surprising aspect of this treatment is that even though the measured values of r and h are in error, the steady-state strain rate, έ _s , predicted from the ratio έ _s = r/h agrees closely with the actual value.