Case Study of Failure in Gray Cast Iron Brake Disc Under Racing Application

This article analyzes a failure of a disc brake used in the Stock Car Pro Series. It focuses on a phase transformation in the pearlitic gray cast iron, commonly occurring during heat treatment. Telemetry data from the racing team, along with samples of brake discs, were utilized for this study. The aim was to explore the potential causes leading to catastrophic wear and failure of the component under real racing conditions. The analyzed brake disc exhibited catastrophic wear due to abrasion, adherence, and material transfer between the disc and brake pads. Through metallographic investigation using optical and scanning electron microscopy, a phase transformation was identified in the outer layer of the brake disc, which may have contributed to its reduced lifespan. Surface hardness was evaluated using a Vickers microhardness tester, revealing that rapid temperature increases induced tensile and compressive stresses, resulting in austenitization and eutectoid transformation in the cooling process.