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2004年底在黑龙江某地的维修检查中发现某铁路货车1位摇枕裂断,整个断面均为新断面,无旧痕。在裂纹源附近的断口分别进行扫描电镜和金相观察检验,测试了摇枕材料的常规理化性能指标。结果表明断口面上可见人字状裂纹扩展台阶,由摇枕的底部向上部扩展,断口并无明显疲劳断裂贝纹线特征;裂纹源区铸造缺陷及局部富含大量有害元素,如Pb、Sn、S等;常规理化性能检验结果符合标准要求。综合分析认为,摇枕裂断属于脆性断裂,与多种因素相关,但是裂纹源区铸造缺陷及局部富含大量有害元素应是造成疲劳裂纹萌生和扩展的主要原因。
The end of 2004 in Heilongjiang, somewhere in the maintenance inspection found a railroad car wreck, the entire section is a new section, no old marks. In the vicinity of the crack source fracture were examined by scanning electron microscopy and metallographic observation, testing the bolster material physical and chemical properties of conventional indicators. The results show that the extension of the herringbone crack at the fracture surface is broadened from the bottom of the bolster to the upper part of the bolster, and there is no obvious feature of fatigue fracture in the fracture surface. The casting defects in the source region of the crack are locally enriched with a large amount of harmful elements such as Pb, Sn , S, etc .; conventional physical and chemical properties test results meet the standard requirements. The comprehensive analysis shows that the crack of the bolster belongs to the brittle fracture, which is related to many factors. However, the casting defects in the source region of the crack and the local enrichment of a large number of harmful elements should be the main reason for the initiation and propagation of the fatigue crack.