Fracture analysis of a castellated shaft

In this paper, an in-service fracture of a castellated shaft was investigated. Visual inspection, SEM observation on the fracture surface, hardness test and microstructural analysis were performed to determine the cause for the fracture. The results showed that the immediate cause for such a failure was the overload impact and torsional deformation. However, deficient hardness of the hardening layer contributed to this failure as an additive factor.