The Influence of Microstructure on the Hardness of Car Brake Discs

Various exploitation influences and the resulting abrasion, erosion or other forms of corrosion destruction can greatly cause changes in the microstructure of car brake discs, thereby reducing their service life and reliability. Due to its properties, gray cast iron is mostly used for conventional car brake discs and as such is subject to the negative influences of the previously mentioned factors. In order to assess this influence and numerically relate it to the actual condition of the discs in operation, the hardness and microstructure of used car brake discs divided into three groups were measured. An analysis of hardness measurement results was conducted alongside micrographs. The findings are presented graphically, with discussions on how microstructure influences hardness and how changes in microstructure affect the hardness of car brake discs. By analyzing microstructure imaging, it can be concluded that different groups of brake discs exhibit varying microstructures. In addition, it was found that there are significant changes in the measured hardness of discs with different operating cycles. The test results should contribute to the optimization of material production processes. The research findings presented in this study could help in proper brake disc maintenance and determining optimal service intervals for replacement.