Evaluation of rolling contact fatigue crack path in high strength steel with artificial defects

• Synchrotron radiation micro-computed tomography imaging detects rolling contact fatigue cracks.
• Detected cracks are composed of vertical and horizontal cracks originating from artificial defects.
• Finite element analyses simulating the above observation results are conducted.
• The possibility of mode II and III propagation of vertical and horizontal cracks is revealed.
• Interaction between vertical and horizontal cracks plays key role in the propagation of cracks.

The objectives of the present paper are to clarify the rolling contact fatigue (RCF) crack path in high strength steel with artificial defects using synchrotron radiation micro-computed tomography (SR micro CT) imaging and to discuss the mechanism of RCF crack propagation by finite element (FE) analysis. Two crack types, a vertical crack and a horizontal crack, were observed around the artificial defect by SR micro CT. The stress intensity factor (SIF) of horizontal cracks, calculated by FE analysis, increased by the existence of vertical cracks. The interaction between these two crack types dominates RCF crack propagation originating from artificial defects.