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    60Si2CrA Ⅱ型弹条断裂原因

    Fracture reason of 60Si2CrA type Ⅱ spring bar

    • 摘要: 某线路中的60Si2CrA热轧弹簧圆钢Ⅱ型弹条在服役6 a多后断裂。采用宏观观察、化学成分分析、硬度测试、金相检验、断口分析等方法对其断裂原因进行了分析。结果表明:弹条表面的防腐涂层剥落使其长时间暴露在腐蚀介质中,并形成了腐蚀凹坑,腐蚀凹坑降低了弹条疲劳强度并引起应力集中,裂纹在该处萌生并不断扩展,最终发生腐蚀疲劳断裂。

       

      Abstract: The type II spring bar of 60Si2CrA hot rolled spring round steel in a certain line fractured after more than 6 years of service. The fracture reasons were analyzed by macroscopic observation, chemical composition analysis, hardness test, metallographic examination and fracture analysis. The results show that the anti-corrosion coating on the surface of the bullet strip was peeled off, which made it exposed to the corrosive medium for a long time and forms corrosion pits. The corrosion pits reduced the fatigue strength of the bullet strip and caused stress concentration. The cracks initiated and propagating here, and finally the corrosion fatigue fracture occurring.

       

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