制动杠杆螺栓的断裂原因

Reason for Fracture of Brake Lever Bolts

采用光学显微镜、扫描电镜、能谱分析仪等对机车制动杠杆螺栓的断裂原因进行了分析。结果表明:螺栓的断裂形式为由应力腐蚀造成的沿晶脆性断裂;螺栓在服役时其断裂处所受到的较大弯曲应力作用,以及螺栓的恶劣服役条件是螺栓断裂的外在原因,而螺栓组织中存在的沿轧制方向分布的带状铁素体、较大的夹杂物是螺栓断裂的内在原因;加强螺栓材料的质量控制并优化螺栓的热处理工艺后,螺栓没有再出现过断裂。

The fracture reason for locomotive brake lever bolts were analyzed by optical microscope,scanning electron microscope,and energy spectrum analyzer.The results show that the fracture mode of bolts was intergranular brittle fracture caused by stress corrosion.The external reasons for the fracture of bolts included the large bending stress on the fracture during service and severe service conditions of bolts;the internal reasons for the fracture included the banded ferrite distributed along the rolling direction and large inclusions in the microstructure of bolts.After strengthening the quality control of raw material of bolts and optimizing the heat treatment process of bolts,no fracture occurred.