Co-Cr3C2 coating incorporating grain refinement and dislocation density gradient to enhance wear resistance of 24CrNiMo steel

Abstract

High-speed train brake discs, crucial components of the braking system, predominantly fail due to high-temperature wear that critically affects their performance and lifespan. Here, we introduce a novel method that incorporates ultrasonic shot peening with Co-Cr₃C₂ particles to create a composite modified layer (referred to as UEG) on the surface of 24CrNiMo brake discs. Friction test results show that UEG-treated samples maintain a more stable coefficient of friction and exhibit lower wear rates across a temperature range of 25–600 °C compared to Untreated samples. Particularly at 600 °C, the wear rate of UEG-treated samples is reduced by 72 %. Detailed experiments and analyses have determined that the enhancements in high-temperature stability and wear resistance of UEG-treated samples are due to the presence of grain refinement and a gradient in dislocation density. These findings suggest that UEG treatment holds substantial potential for improving the high-temperature wear resistance of brake discs, providing innovative insights and approaches for their application.