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.

首次研究了通过共晶凝固工艺制备的TiB ₂增强高模量钢的疲劳裂纹扩展机理。使用原位扫描电子显微镜（SEM）测量了TiB ₂增强钢的疲劳裂纹扩展率（FCGR），并将其与低碳铁素体钢进行了比较。表明TiB ₂的FCGR钢筋总是比低碳钢低。其主要原因可归因于杨氏模量的提高和优异的固有疲劳裂纹抵抗性，以及由于多种疲劳裂纹扩展机制导致不同的裂纹闭合水平而产生的外部原因。另外，分形分析表明在疲劳裂纹扩展期间几乎没有发生界面剥离。发现在研究的TiB ₂增强钢中存在四种类型的疲劳裂纹扩展行为，以综合的方式有助于其优异的疲劳裂纹扩展性能。