对钢筋混凝土桥梁中的钢筋进行了显微组织与疲劳性能测试,研究了不同应变量下钢筋的疲劳性能变化,并对疲劳断口形貌和疲劳试验前后的显微组织进行了观察。结果表明,桥梁用钢筋的组织为铁素体+珠光体混合组织;随着总应变量的增加,钢筋的最大应力逐渐增加,而疲劳寿命逐渐降低;在疲劳性能试验后,钢筋中的位错密度明显上升,位错在疲劳载荷作用下,不断缠结和聚集形成胞状结构,在这个过程中细小的第二相可以起到钉扎位错的作用,使得钢筋的疲劳性能提高。 The microstructure and fatigue properties of steel bars in reinforced concrete bridges were tested. The fatigue properties of steel bars under different strain levels were studied. The appearance of fatigue fracture and the microstructure before and after fatigue test were observed. The results show that the microstructure of the bridge is ferrite + pearlite mixed structure. With the increase of the total strain, the maximum stress of the steel increases gradually and the fatigue life decreases gradually. After the fatigue test, the dislocation The density increases obviously. Under the action of fatigue load, the dislocations continue to tangle and aggregate to form cellular structures. During this process, the fine second phase can act as a pinning dislocation and improve the fatigue performance of the reinforcing bars.