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

damage to the cracked surface throughout the investigation. To inspect the fracture surface, the as-received rotor was cautiously divided into two (**Figure 2c** and **d**) along the fracture line. The broken surface was critically examined to identify abnormalities and the origin of the fracture. Visual inspection was done using a stereo microscope (SZ-CTV Olympus, Japan). Samples for chemical composition and microstructure analyses were obtained from the swan-neck region of the as-received rotor using a spark optical emission spectrometer (OES) and scanning electron microscope, respectively. The rotor swan neck thickness was determined using a TI-007X Precision Ultrasonic Wall Thickness Gauge.

The metallographic samples were extracted from the damaged section of the rotor and prepared to identify any microstructural irregularities. The samples were etched with a 2% Nital solution to reveal the pearlitic structure of the GCI rotor. For microstructural investigation, the samples were observed under a light optical microscope (LOM) and a scanning electron microscope coupled with energy dispersive X-ray microscopy (SEM-EDS). A scanning electron microscope (JEOL JSM-IT200) and

Olympus optical microscope (Leica, DM2500M, Germany) were used for the microstructure analysis. A Brinell hardness tester was employed to measure the rotor's hardness on the friction surface and the disc hat. The average value of the hardness was reported. The fractographic investigation was accomplished using SEM-EDS to determine the constituent phases found on the cracked surface. **Figure 3** illustrates the systematic method adopted to understand the root cause of the rotor failure.
