Monitoring of Elastoplastic Fracture Behavior of HSLA Steel Using Acoustic Emission Testing

The present study explores using acoustic emission testing (AE) to monitor the elastoplastic fracture toughness (JIC) of high-strength, low-alloy (HSLA) steel in two different orientations. Acoustic emission signals generated during the tests were found to be higher during bulk yielding upon initial loading, after which they decreased during intermediate loading before increasing again. The acoustic emission signals generated were used to correlate with the JIC values determined from unloading compliance tests. The point of crack initiation estimated by AE is lower than that determined by the unloading compliance tests. Beyond the point of crack initiation determined by AE, the acoustic emission signals generated increased rapidly, which is attributed to crack growth. The results of AE during crack initiation are supported by the peak amplitude of the acoustic emission signals. The possibility of using AE data to estimate fracture toughness values has also been explored for HSLA steel.