重型汽车制动鼓开裂分析

摘要

重型汽车的制动鼓材料为灰口铸铁，在使用中容易开裂。为此，对开裂的制动鼓进行了宏观检查、金相检验、化学成分分析、硬度测试及断口分析，以揭示制动鼓开裂的原因。结果表明，由于石墨与基体的结合强度弱，且石墨的强度、膨胀系数等与基体存在明显差异，导致裂纹起源于石墨片，并在拉应力、摩擦力的作用下沿制动鼓轴向扩展。%Brake drum of heavy truck,made of gray iron,cracks probably in service.For this reason,the brake drum in which the crack has formed was subjected to macroscopic and metallographic examinations,chemical composition analysis,hardness test and fracture analysis to reveal the reason why it cracks.From above physical and chemical test results it was found that the crack formed initially in graphite flake due to both weak adhesion of the graphite to the matrix and obvious difference between them in strength and expansion coefficient,and then propagated further by the action of tensile stress and fractional force.