Fracture reason of the 60Si2Mn steel wire rod

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.