In this paper, the effect of tempering on crack propagation and fracture mechanism of a cold-work tool steel is investigated. Acoustic emission (AE) monitoring with fuzzy C-means (FCM) clustering was developed in order to detect the different fracture mechanisms during fracture toughness tests of specimens tempered at 5 different temperatures from 0 to 575 ◦C. The obtained AE signals were analyzed by considering AE parameters such as amplitude, count, frequency, energy, and classified using FCM. Scanning electron microscopy (SEM) observation was also used to determine the different fracture mechanisms. The results show that the AE characteristics and FCM classification are efficient tools in the analysis of AE signals to detect fracture mechanism, and there is a good agreement with the results of these tools and microscopic observation by SEM.
