AE analysis of damage processes in cast iron and high-strength steel at different temperatures and loading rates

Abstract

Acoustic emissions originating from damage processes in nodular cast iron and high-strength steel were analyzed. Three point bending tests of notched and precracked bend bars were performed to investigate the onset of crack growth at quasi-static and dynamic loading rates and temperatures of 20 and −40 °C. Additionally, the materials were subjected to uniaxial tensile loading. It was found that the steel emits most of the transient acoustic signals during globally elastic behavior. In contrast, for the cast iron, most of the transient acoustic emissions were detected at small plastic strain. Since the acoustic emission were correlated with the volume of the plastically deformed material in the steel, the size of the plastic zone during fracture toughness testing was estimated. Furthermore, the onset of stable crack initiation was derived from the acoustic signal.