Feasibility of studying 460 MPa high-strength steel affected by strain aging with acoustic emission method

Strain aging significantly influences the behavior of partially damaged structural steel. The effects of strain aging can be determined based on mechanical experiments, but the sampling process causes further damage to the structures. To explore the possibility of using nondestructive testing (NDT) technology to distinguish the strain aging effects on steel materials, this study investigates the characteristics of acoustic emission (AE) signals for high-strength steel (HSS) affected by strain aging. First, different strain aging effects were applied to 460 MPa HSS specimens. Second, pencil lead break (PLB) tests were performed on the specimens with strain aging, and the generated AE signals were recorded. Finally, tensile tests were conducted, that the strain aging effects on mechanical behavior were determined. The obtained AE signals were compared by extracting the AE parameters and analyzed in the frequency and time-frequency domains with a fast Fourier transform (FFT) and a wavelet transform (WT), respectively. The study shows that the strain aging effects change the characteristics of the AE signals. Compared to the prestrain, the aging time has a more pronounced impact on the AE behaviors. This research proposes a possible NDT method to determine the effects of strain aging on steel materials. Experimental data are provided to detect the degree of partial damage to 460 MPa HSS owing to strain aging using the AE method.