Fracture Analysis of 60Si2MnA Spring Rods for Laying Rail during Fatigue Life Test

Fatigue life of a batch of 60Si2MnA steel spring rods didn’t reach the required value. The failure spring rods were analyzed by means of macro and micro observation of fracture surface, metallographic examination, hardness testing and chemical compositions analysis. The results show that the failure mode of the spring rods was fatigue fracture resulting from the co-effect of bending and twisting. The main reason for the early fracture of the spring rods was carbon content of their raw material was lower than the standard required value to 60Si2MnA steel, which resulted in the hardness of the spring rods was lower than the technical requirement after heat treatment and reduced the fatigue properties of the spring rods heavily. Another reason for the shorter fatigue life was that there was net-shape ferrite structure at the local surface of the spring rods because of decarburization, which made fatigue cracking source generate easily.