W2Mo9Cr4VCo8推杆断裂原因分析

W2Mo9Cr4VCo8（M42）推杆在工作中发生断裂,将断裂的、试验后未断裂的三根及未进行试验的,共5根同规格的推杆进行对比,通过扫描电镜微观形貌、硬度、金相组织进行分析。并将完好推杆进行人为弯曲断裂试验,与原断裂推杆断口进行对比。结果表明,M42推杆为过载断裂,断裂原因与推杆端面加工磨削不当导致端面截面尺寸比标准尺寸偏小有关。截面尺寸变小后,紧靠推杆的钢球与该端面撞击后发生偏差,导致推杆除了承受压应力还叠加了弯曲或扭转应力。建议进一步分析异常应力的来源,并加强控制推杆端面的截面厚度的尺寸。

Fracture Failure Analysis of Push Rod of W2Mo9Cr4VCo8 Steel

The push rod of W2Mo9Cr4VCoS（M42） steel was fractured during working process. Including fracture push rod and three push rods without fracturing after testing and another push rod without any test, the five push rods with the same specification were contrasted each other. The five samples were analyzed by SEM microscope organization, hardness and metallography observation. Then man-made bending frac- ture testing was processed for undamaged push rod and was contrasted with the fracture push rod. The re- suits showed that the main reason of the failure was overload fracture. The inappropriate grinding on the end of the rod caused the size of the fracture cross-section was less than the standard. As a result, the stell ball closing to push rod with the end after crash happend deviation, lead to push rod in addition to with- stand the compression stress, superposition of the bending or torsional stress. It was suggested to further analyze the sources of the abnormal stress and strengthen the control of the size of the push rod end of cross-section.