Fracture Failure Analysis of Piston Rod of Oil Cylinder

The fracture of the piston rod under high frequency quenching treatment was occurred in the early use. The fracture cause of piston rod was analyzed by means of macroscopic and microscopic fracture ananlysis, chemical composition analysis, micro-hardness analysis and microstructure analysis. The results indicate that the fracture mechanism of the piston rod was fatigue fractue. Without the induction hardening layer, the fatigue resistance of the piston rod was reduced. The stress concentration was induced by the existence of micro-cracks in the subsurface. Thus the fatigue source was formed in the subsurface. Without tempering treatment, the fracture of piston rod was accelerated because of low hardness and intensity of the core area.