Differences in the Acoustic Emission Characteristics of 345 MPa Normal-Strength Steel and 460 MPa High-Strength Steel

This study characterized 345 MPa normal-strength steel (NSS) and 460 MPa high-strength steel (HSS) with the acoustic emission (AE) technique. Pencil lead break (PLB) and tensile tests were performed, and the generated AE signals were recorded. The AE signals from the PLB tests were converted into the frequency and time-frequency domains via a fast Fourier transform (FFT) and wavelet transform. The AE signals generated during the tensile process were divided into four stages for analysis. The AE parameters, such as the counts, amplitude, hit and duration, were extracted from the signals. An FFT was conducted to obtain the features of frequency spectrum at each stage. The comparisons revealed the similarities and differences in the AE characteristics between the two steels. It was found that the energy of the AE signals for the 460 MPa HSS was less overall than that of the 345 MPa NSS. The analysis results indicated that the AE technique is a method that can potentially be used to distinguish the two steels, and additional studies for accurate identification are needed. As 460 MPa HSS is being widely used but related AE studies are limited, this study provides data for additional investigations of the damage in HSS structures with the AE method.