Evaluation of the Influence of Fatigue Crack Closure on Eddy Current Testing Signals
In the previous study, it has been found that amplitude of ECT signal of fatigue cracks which are introduced in type 316 and 316L austenite stainless steels decrease after heat treatment. As the result, evaluation of the ECT signals with error leads to the underestimation of fatigue cracks sizing. In this study, the relation between loading conditions of fatigue test and ECT signal change is investigated, in order to figure out the phenomenon. The results show the amplitude change of eddy current is related to the crack tip stress intensity factor K and stress ratio R.