Characteristics of microscopic crack and propagation life of forged steel brake disc for high-speed train

摘要

The organizational structure evolution and life prediction method of brake disc with multi cracks are studied. This thesis analyzed the microstructure transformation in the process of crack propagation through observing the microstructure and anatomy of the failed brake disc. Based on the NASGRO theory and fracture mechanics method, the fatigue life of forged steel brake disc with single crack was calculated under different braking conditions, which is formed by multiple hot spots. Also, on the basis of the coupling effect between multiple cracks, a fatigue life prediction method for forged steel brake disc with multiple cracks was proposed. By comparing the fatigue life with or without considering the crack coupling effect, the thesis proposed that the fatigue life of brake disc is significantly lower than that of brake disc with single crack when it comes to crack coupling effect. The results of bench test are basically consistent with the hypothesis. Therefore, it is of great significance to improve the contact state of brake disc and avoid the appearance of hot spots for prolonging the crack propagation life of brake disc.