某型装甲车底盘系统平衡肘断裂分析

目的 探讨平衡肘断裂原因，消除故障隐患和防止类似问题发生。方法 采用单反相机、扫描电镜、金相显微镜、硬度计、电感耦合等离子体原子发射光谱仪等对平衡肘故障件的宏观形貌、微观形貌、显微组织、硬度、化学成分等开展表征分析。利用ANSYS有限元软件对内花键进行应力分析，并对2次淬火的试样尺寸进行测量。结果 右4平衡肘裂纹源断口为撕裂和沿晶的混合断裂，断口芯部为解理断裂；右2平衡肘断口内表层淬火层为沿晶和韧窝的混合断裂，芯部为韧性断裂。故障件显微组织和化学成分均无明显变化，仅表面硬度值较实验前降低了7%~9%。断裂失效原因是由于内花键二次高频淬火后收缩变形，齿根圆弧部位在腐蚀介质和交变载荷的共同作用下因应力集中而形成裂纹，在后期循环应力作用下，裂纹继续扩展导致疲劳断裂。结论 从加强腐蚀控制和热处理的角度出发，通过选用抗腐蚀性能好的材料、进行表面防护处理、控制车体环境的湿度和温度等加强腐蚀控制，并增加采用电脉冲等方式对变形花键齿进行修形工序严格控制尺寸范围，避免产生过大拉应力，确保装备质量。

Fracture Analysis of Balancing Elbow in Chassis System of an Armored Vehicle

The work aims to explore the reasons for the breakage of the balance elbow, eliminate hidden troubles and prevent similar problems from occurring. A camera, a scanning electron microscope, a metallographic microscope, a hardness tester, an inductively coupled plasma atomic emission spectrometers were used to characterize and analyze the micromorphology, microstructure, hardness, chemical composition of the faulty balance elbow parts; ANSYS finite element software was used to conduct stress analysis on the internal spline, and the dimensions of the twice quenched specimen were measured. The results showed that the crack source fracture of the right 4th balanced elbow was a mixed fracture of tearing and inter-granularity, and the core of the fracture was a cleavage fracture; While the inner surface quenching layer of the fracture of the right 2nd balanced elbow was a mixed fracture of intergranular and dimples, and the core was a ductile fracture. There was no significant change in the microstructure and chemical composition of the faulty part, except that the surface hardness value decreased by 7% to 9% compared with that before the experiment. The balance elbow fracture was due to the shrinkage deformation of the internal spline after secondary high-frequency quenching. The combined action of corrosive media and alternating loads caused stress concentration in the arc part of the tooth root to form cracks. In the later cycle, cracks continued to expand under the action of stress, leading to fatigue fracture. Finally, suggestions for improvements are supplied to ensure equipment quality. The corrosion control should be strengthened by selecting materials with good corrosion resistance, surface protection treatment, and controlling the humidity and temperature of the vehicle environment. By increasing the use of electric pulses and other methods to modify the deformed spline teeth, the size range can be strictly controlled to avoid excessive tensile stress.