某乘用车抗扭拉杆由ADC3合金压铸成型，售后出现断裂，断裂位置和形式相同。为找出断裂原因，对断裂 的抗扭拉杆进行了断口分析、化学成分分析和显微组织分析，随后对同批次的抗扭拉杆进行了力学性能分析检查，结果 表明，抗扭拉杆断裂属脆性断裂，裂纹起源于拉杆支架中部应力槽附近，抗扭拉杆成分满足标准要求，显微组织正常。但 同批次抗扭拉杆ADC3合金真实力学性能低于设计要求，综合分析表明，抗扭拉杆断裂的根本原因是材料真实强度不 足，次要原因是内部存在铸造缺陷。 综合考虑多方因素后，在不改变抗扭拉杆结构和设计条件下，选用ZL111合金重力 铸造成型制造抗扭拉杆，制造出的抗扭拉杆满足实际要求，取得了较好的效果。

Passenger vehicle torque reactor were manufactured by die-casting and ADC3 alloy, fracture occurred after sale in the same position and form. In order to find out the reason of fracture, fracture analysis, chemical composition analysis and microstructure analysis were carried out on the broken torque reactor, and then the mechanical properties of the same batch of torsion bar were analyzed and examined. The results show that the fracture of the torque reactor belongs to brittle fracture, the crack originates near the stress groove in the middle of the tension bracket, the composition of the torque reactor meets the standard requirements, and the microstructure is normal. However, the actual mechanical properties of ADC3 alloy of the same batch of torque reactor are lower than the design requirements. The comprehensive analysis shows that the root cause of the fracture of the torsional tie rod is the lack of real strength of the material and the secondary cause is the internal casting defects. Considering various factors, it is concluded that under the condition of not changing the structure and design of the torque reactor, ZL111 alloy is adopted for forming the torsion bar by recast. The torque reactor meets the actual requirements and achieves good results.