The acoustic emission measurement of cleavage initiation near the ductile brittle transition temperature in steel

By use of the AE technique, the microcleavage fracture process in HSLA steel has been studied near the ductile-brittle transition temperature. Upon loading, several AE events were detected before final instability. Multiple origins of the cleavage were evident ahead of the fatigue crack front. It was concluded that weakest link hypotheses were not applicable near the ductile-brittle transition temperature. Good correlations were found between AE data and cleavage facets as a function of stress intensity factor.