The effect of preliminary cyclic loading on acoustic emission parameters and damage of structural steels

Abstract Preliminary cyclic loading of structural low-carbon and 15Cr2MnMoV steels specimens to a relative lifetime of 0.3, 0.5 and 0.7 were conducted. After preloading, tensile tests with the acoustic emission (AE) registration were performed and the effects of preliminary cyclic loading on the intensity (dNAE/dt), the cumulated number (ΣNAE) and energy (ΣEAE)of acoustic emission signals, and the bAE-value (the slope coefficient of cumulative distributions of the AE signals amplitudes) were investigated. According to the test results, the dependencies of the AE parameters on the relative deformation were plotted. An analysis of these dependencies made it possible to distinguish the stages of changes in AE characteristics that correlate with the stages of changes in mechanical properties and material damage. New relations connecting acoustic emission parameters to the relative number of cycles before fracture of steels studied were obtained.