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斜井箕斗拉杆断裂原因分析

Fracture cause analysis of inclined shaft skip pull rod

  • 摘要: 某煤矿用原煤提升装置斜井箕斗拉杆,材质45钢,使用35 d发生拉杆断裂事故。本文借助电子探针、直读光谱分析仪、硬度计、冲击试验机、拉伸试验机和金相显微镜,对箕斗拉杆进行了断口形貌、化学成分、硬度、冲击性能、拉伸性能和显微组织分析,讨论了其失效原因。结果表明:箕斗拉杆失效模式为脆性解理断裂,其主要原因是拉杆金相显微组织呈网状铁素体、珠光体和魏氏组织、局部粗大晶粒,导致箕斗拉杆抗冲击性能严重降低;在拉杆的R角处存在明显的车刀痕加工缺陷加剧了应力集中,箕斗拉杆由于冲击力的作用发生了早期解理断裂。

     

    Abstract: The inclined shaft skip pull rod of the raw coal lifting device for coal mines was made of 45 steel. After 35 d of use, a pull rod fracture accident occurred. The fracture morphology, chemical composition, hardness, impact properties, tensile properties and microstructure of the skip pull rod were analyzed by electron probe, direct reading spectrometer, hardness tester, impact testing machine, tensile testing machine and metallographic microscope, respectively, and the failure cause was discussed. The results showed that the failure mode of skip pull rod was brittle cleavage fracture. The main reason was that the metallographic microstructure of pull rod consisted of reticular ferrite, pearlite and widmanstatten structure with some local coarse grains, which led to a significant reduction in the impact resistance of skip pull rod. At R-angle of pull rod, there was a clear cutting tool mark processing defect, which intensified the stress concentration, and the skip pull rod undergoed an early cleavage fracture due to the impact force.

     

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