Study on the estimation of high temperature fracture parameter for mismatched weld creep cracks

Evaluation of the creep crack growth is very important for predicting the life of high temperature structures. Since Ct can uniquely characterize creep crack growth from the small scale creep stage to the extensive steady state creep stage, an engineering estimation method of Ct was proposed for a crack located in the weld with mismatched material properties between the base material and the weld material based on the simulation results of compact tension specimens. For the crack located in the center of welding seam, Ct was estimated by the proposed method under the small scale creep stage and by the reference stress method under the extensive steady state creep stage; in this way, Ct was estimated under the whole creep stage. The estimated results agreed well with the simulation results if the width of welding seam of h was no smaller than the size of the stress intensity factor dominance zone.