ACOUSTIC EMISSION DURING TENSILE DEFORMATION OF SMOOTH AND NOTCHED SPECIMENS OF NEAR ALPHA TITANIUM ALLOY

Acoustic emission (AE) generated during tensile deformation of smooth and notched specimens of near Alpha titanium alloy have been studied. A few tests carried out with both types of specimens were also interrupted in order to correlate with the damage mechanism. The results have shown higher acoustic emission during yielding and reduced AE at higher strain level in the smooth specimen. A peak in the root mean square (RMS) voltage at higher strain was associated with the initiation of microcrack. In the notched specimen, localized deformation at the notch tip gives rise to detectable AE in the region prior to macroscopic yielding and gives intense AE at lower strain compared to net section yielding. This is characterized by peak amplitude distribution of hits in which majority of the hits are shifted to lower amplitudes in notched specimens as compared to the smooth specimen. The AE results have been supported by microstructural investigations.