**Figure 14.**

*A schematic illustration of the mode of failure of the rotor.*

### *Root Cause Failure Analysis of Castings: A Case Study of a Brake Rotor DOI: http://dx.doi.org/10.5772/intechopen.107950*

subjecting this region to higher stress during service. Due to the high thermal expansion potential of the inclusion particles, they would disintegrate into smaller particles [11, 35] and produce cavities that generate microcracks around the inclusion particles (**Figure 9**). Also, during the application, the brake rotor continuously experiences thermal (heating and cooling) and mechanical loadings that cause local concentrations of strain, induce residual stresses and initiate microcracks because of the thermal expansion mismatch between the inclusion particles and the pearlitic matrix. These microcracks propagate further through the interface between the graphite-pearlitic matrix (**Figure 7b**) and ultimately cause the rotor's failure.

After understanding and establishing the failure root cause(s), it is essential to formulate corrective or preventive measures/actions to forestall future recurrence. Judging from the various inspections performed on the failed rotor, the outcomes indicated that the inclusions (sand and slag materials) embedded in the rotor's swan neck during the casting process were responsible for its premature failure. This observation indicated that the failure root cause originated from the rotor manufacturing, implying that the preventive recommendations should be focused on the casting process to ensure quality castings. Therefore, the following strategies should be strictly implemented and practiced by the metal casters for casting quality enhancement and to avert nonmetallic inclusions during the following casting operations.

