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以存在表面裂纹的蠕墨铸铁制动盘为研究对象,通过对裂纹进行宏观观察、微观分析、金相组织检验及布氏硬度测试,分析了制动盘体表面裂纹的性质与成因。结果表明,裂纹属于热疲劳裂纹,制动过程中循环热载荷引发的应力是导致制动盘表面裂纹产生的主要原因。制动盘在制动循环中表面经历高、低温的剧变过程,在不完全冷却的条件下,盘体摩擦面的不均匀温度场分布产生较大热应力,当应力超过材料强度时就会在盘体表面萌生热疲劳裂纹,并不断向内部扩展。为减少热疲劳裂纹的产生,建议严格监控盘体表面温度,定期检查盘体表面。
Taking the vermicular cast iron brake disc with surface cracks as the research object, the nature and causes of the surface crack of the brake disc body were analyzed by macroscopical observation, microscopic analysis, microstructure test and Brinell hardness test. The results show that the crack belongs to the thermal fatigue crack, and the stress caused by the cyclic thermal load during the braking process is the main cause of the crack on the surface of the brake disk. Brake disc surface in the brake cycle experienced high and low temperature drastic changes in the incomplete cooling conditions, the disc friction surface uneven temperature field distribution have a greater thermal stress, when the stress exceeds the strength of the material will be in the Thermal fatigue surface crack initiation, and continue to expand to the interior. In order to reduce the occurrence of thermal fatigue cracks, it is recommended to strictly monitor the temperature of the surface of the disk body and regularly check the surface of the disk body.