FRACTOGRAPHIC OBSERVATIONS OF STRETCHED REGIONS IN FRONT OF FATIGUE CRACKS

A recent analysis (1) of the stretched region formed in fracture surfaces between the farique crack and overload fracture regions indicated that the regions could be related to the plane-strain fracture toughness, KIC . Similar fractographic observations on a metastable-austenitic steel do not follow this relationship. From three separate specimens of this investigation, the stretched regiond were observed to be 2.7 to 7.6 ~ in width. .K alloy