某60Si2Mn钢盘条在卷簧过程中发生断裂。采用宏观观察、化学成分分析、金相检验、夹杂物分析、扫描电镜分析等方法对该盘条的断裂原因进行分析。结果表明:在卷簧前及卷簧初期的拉拔过程中,盘条表面受到了严重的挤压或擦蹭,使组织变形,并形成了隐晶马氏体;在后续的拉拔过程中,盘条内部应力集中处萌生了微裂纹,裂纹不断扩展,最终导致盘条断裂。

A 60Si2Mn steel wire rod fractured during the coiling process. The fracture reason of the wire rod was analyzed by means of macroscopic observation, chemical composition analysis, metallographic examination, inclusion analysis and scanning electron microscope analysis. The results show that the surface of the wire rod was seriously squeezed or rubbed before the coil spring and during the initial drawing process of the coil spring, resulting in tissue deformation and the formation of cryptocrystalline martensite. In the subsequent drawing process, microcracks were initiated at the internal stress concentration of the wire rod, the cracks continued to expand, eventually led to the fracture of the wire rod.