Investigations into non-metallic inclusion crack area characteristics relevant for tooth root fracture damages of case carburised and shot-peened high strength gears of different sizes made of high-quality steels

摘要

Case carburised and shot-peened high-strength gears can fail by tooth root bending failures in the very high cycle fatigue range of the S-N-curve due to crack initiation at a non-metallic inclusion. It is essential to understand crack characteristics and mechanisms of such sub-surface initiated cracks, which are different to surface initiated cracks, in order to further increase the gear performance. This paper discusses the results of detailed analyses of such fractured surfaces.