中文摘要：

采用MTS Landmark 370型万能机研究了全壁厚铁素体/贝氏体双相X80管线钢的疲劳性能,并通过SEM方法对钢的组织及断口进行了分析。结果表明,铁素体/贝氏体双相钢中的铁素体有大角度晶界,而贝氏体由小角度晶界的贝氏体铁素体及细小的马氏体/奥氏体（M/A）岛构成。疲劳裂纹主要在钢板表面凹坑处萌生;疲劳强度S与寿命N的关系为S=2 973×N-0.14;在裂纹扩展过程中,铁素体晶界、贝氏体及贝氏体组织中的M/A岛对疲劳裂纹扩展有抑制作用。

英文摘要：

The fatigue property of a ferrite/bainite duple phases X80 pipeline steel was examined on a MTS Landmark 370 universal testing machines, and the microstructure and fractures were observed by means of SEM. The results show that the ferrite grains in ferrite/bainite microstrueture consist of large angle grain boundaries, while the bainite consists of bainite ferrites with low angle grain boundaries and martensite/austenite （M/A） islands.The fatigue crack is mainly generated at the surface scallops of the rolled steel plate.The relation of the fatigue strength （S） to the fatigue life （N） is S = 2 973×N-0.14.The ferrite grain boundaries, bainite and M/A islands could inhibit crack propagation.