中文摘要：

采用超声疲劳试验机研究SUJ2轴承钢的超长寿命疲劳。结果表明：对于复合氧化物和TiCN裂纹源,裂纹从夹杂物与基体界面处萌生;铁、铬合金碳化物裂纹源则为夹杂物本身开裂。颗粒状亮面（GBF）相对尺寸正比于裂纹源处夹杂物边缘的应力强度因子范围1/ΔK2inc,对于本实验的SUJ2材料,当ΔKinc〉8MPa·m1/2时GBF不再形成。通过数据拟合得到了GBF内裂纹扩展规律：area~（1/2）_（GBF）/area~（1/2）_（inc）=（m_1＋m_2N_f）~（m_0）,证实了Paris公式可以用来描述GBF内的裂纹扩展。

英文摘要：

Ultra-long life fatigue behavior of SUJ2 bearing steel was studied by ultrasonic fatigue testing machine.The results show that,for the crack origin of composite oxide and TiCN,crack initiates from the interface between inclusion and matrix,and for the iron-chromium carbide crack origin,the inclusion itself cracks.The relative GBF（granular bright facet）size is proportional to 1/ΔK_（inc）~2.GBF is no longer formed when ΔK_（inc）8MPa·m~（1/2） for SUJ2 bearing steel.The crack propagation rule in GBF is obtained by data fitting,it is verified that Paris equation which can describe the crack growth in GBF is verified.