ANALYSIS OF FRACTURE RESISTANCE OF TOOL STEELS BY MEANS OF ACOUSTIC EMISSION

The usage of advanced high strength steels (AHSS) in struc tural automotive components has been broadened in the past few years to satisfy the str ict specifications of the automotive industry. Besides showing excellent strength to weight rations, AHSS have several limitations due to the high loads required in cold forming and cutting tools, which decrease considerably the tooling performances. Therefore, these important forces of im pact provoke unforeseen breakage of the dies. The aim of this research is to study the micromechanica l behaviour and fracture mechanisms (nucleation and crack propagation) during fracture of tool st eels using the acoustic emission (EA) technique. To do that, bending testing specimens of differ ent tool steels were monitored in order to establish a relationship between AE signals and their mechanical behavior (carbide breakage, cracks emanating from them and crack propagation through the metallic matrix).