CREEP‐FATIGUE CRACK GROWTH AND FRACTOGRAPHY OF A TYPE 304 STAINLESS STEEL AT ELEVATED TEMPERATURE

Abstract

Abstract— Creep‐fatigue crack growth behaviour of a Type 304 stainless steel under four types of reversed loading patterns (P‐P, P‐C, C‐P and C‐C) was investigated and the results are discussed in the light of fracture mechanics and fractography. The crack growth rate for all of the four types of loading was successfully correlated in terms of the cyclic integral range λ J. It was unnecessary, for practical purpose, to divide Ay into a fatigue component, λ J f , and a creep component, λ J c , as has been done elsewhere. The transition of the correlating fracture mechanics parameter from fatigue to creep was not necessarily associated with the fracture morphology. This was related to the longer transition hold time in morphology in C‐C type loading compared to C‐P type loading, and was attributed to recovery of grain boundary sliding during the compression hold in the C‐C type loading.