Wake length and loading history effects on crack closure of through-thickness long and short cracks in 304L: Part I – Experiments

A detailed study of the propagation of bidimensional (2D) through-thickness cracks has been conducted on a 304L austenitic stainless steel used in nuclear industry in view of providing a detailed description of the effective driving force to be introduced in numerical simulation of thermal fatigue crack arrays in some critical components. To answer this problem, crack closure is precisely determined for long cracks and 2D short cracks artificially obtained in CT specimens, for different loading conditions. The present results will be used to validate numerical simulations of crack closure presented in a second part as a sister paper.

► Experimental fatigue tests under constant stress intensity factor range were done.
► The influence of crack length on plasticity induced crack closure was investigated.
► For short cracks, the opening ratio is increasing with crack length.
► For long cracks, the opening ratio is independent of crack length and ΔK range.
► The numerical simulation is presented in a second part of this paper.