An alternative correlating parameter for creep crack growth rate and its application: Derivation of the parameter<i>Q</i>

Abstract

The parameter Q* has been proposed for correlating or characterizing creep crack growth rate. The creep crack growth rate has been expressed in terms of an activation process equation, and the parameter Q* was defined as the exponent of the exponential in the thermal activation process equation for da/dt, in which the activation energy is expressed in terms of free energy. CrMoV steel was used for VAMAS round-robin tests, and other materials such as SUS 304 and the Nl-base alloy of Hastelloy-XR were used. For these materials good correlations are obtained. An analytical conclusion about the effect of thickness on crack growth is described.