Detection of crack nucleation and growth in tool steels using fracture tests and acoustic emission

Fracture tests and Acoustic Emission (AE), a technique providing wave-like information, were coupled in this study in order to obtain in-situ data characterization of damage mechanisms. Characteristic AE signals were analyzed and related to micro-mechanical and damage mechanisms taking place in the microstructure. The occurrence of these signals varied depending on the considered steel in terms, for instance, of the quantity of registered signal or the stress at which they started to be recorded. The results of this investigation revealed the stresses at which crack nucleation and propagation processes started to occur in ingot- and powder-metallurgy tool steels with very different microstructural properties, and they provided very helpful information to understand the failure mechanisms acting in these steels.