Frequency spectrum analysis of acoustic emission signal obtained during tensile deformation and fracture of an AISI 316 type stainless steel

Acoustic emission (AE) signals obtained during tensile deformation and fracture of an AISI 316 stainless steel specimens have been analysed in frequency domain. An attempt has been made to correlate the frequency spectra corresponding to various stages of plastic deformation with the physical phenomena occurring. By this mode of analysis, it was possible to distinguish two regions of plastic deformation namely the uniform elongation region upto ultimate tensile strength and necking deformation by their charecteristic patterns. The pattern in the uniform elongation region has indicated that during continuous type AE emission, the extent of waiting time of mobile dislocations at short range obstacles is mainly responsible for the predominant frequencies observed. The lower value of predominant frequency observed during the necking region is attributed to microvoid coalescence and/or crack growth, a less transient phenomenon