On the fatigue crack propagation mechanism of a TiB2-reinforced high-modulus steel

The fatigue crack propagation mechanism of a TiB2-reinforced high-modulus steel fabricated by eutectic solidification process was investigated for the first time. The fatigue crack growth rate (FCGR) of the TiB2-reinforced steel was measured by using in-situ scanning electron microscope (SEM) and it was compared with that of a low carbon ferritic steel. It showed that the FCGR of TiB2-reinforced steel was always lower than that of the low carbon steel. It can be mainly attributed to excellent intrinsic fatigue crack resistance due to improved Young's modulus and the extrinsic reasons ascribed to multiple fatigue crack propagation mechanisms resulting in different crack closure level. In addition, fractographic analysis revealed that almost no interfacial debonding occurred during fatigue crack propagation. It was found that the four types of fatigue crack propagation behavior existed in the studied TiB2-reinforced steel, which contribute to its excellent fatigue crack growth resistance in a synthetical way.