Surface contact fatigue failure of a case hardened pinion shaft

Abstract

An investigation was made to determine the causes of surface contact fatigue failure of a case hardened driver pinion located in the intermediate shaft of a reducer gearbox used in a sugar and alcohol mill. The examination of the component revealed the presence of a cemented layer substantially thicker than that generally specified for pinions devised for this application. This, associated with the massive presence of brittle threadlike carbon-rich cementite phase (Fe 3 C) in prior austenite grain boundaries of the pinion teeth, favored surface crack nucleation and propagation during cyclic loading, leading to spallation of the contact surface with the counterpart gear, which impaired the system's operation. Poor carburization practice was discovered as the root cause of the mechanical failure, thus demanding the implementation of a new manufacturing route to avoid problems in similar load-bearing rotating components.

A Tracking Review on Non Arc Melting Processes for Improved Surface Properties in Metallic Materials

“…Lee et al (2006) further reported that treatment temperatures between 870 o C and 860 o C minimized residual stress without substantially compromising the hardness of the treated case. Stress corrosion cracking, brittle fracture, fatigue failures are main associated failures while carrying out the flame hardening (Rossino et al,2014) due to improper selection and control of thermal process parameters. Grum et al (2001) focused on increasing the hardness by mechanized flame hardening procedure though, the optimal process parameters were not considered.…”