Characterization for crack initiation life, propagation life and total fracture life, respectivery under high temperature creep, fatigue and creep-fatigue conditions.

Abstract

Characterization has been made of crack initiation life, propagation life and total life, respectively, under high temperature creep, fatigue and creep-fatigue interaction conditions for notched specimens of SUS 304 stainless steel. The main results are : (1) The equation for crack propagation life are derived. (2) Crack propagation life is well in accord with the thermal activation equation. (3) Crack propagation life and total life of the notched specimen are well characterized by the temperature-time equivalent parameter T(ln t+C) which looks like the Larson-Miller parameter in the case of the rupture life of the smooth specimen. (4) For prediction of the remaining life in the crack initiation stage, a new method is proposed by using relative notch opening displacement (RNOD).