拉伸保载对2．25Cr1MoV 钢高温低周疲劳行为的影响

摘要

利用液压疲劳试验机,采用轴向应变控制方法在455℃下对2．25Cr1MoV 钢进行高温低周疲劳试验,通过在峰值应变拉伸时保载0,60,600 s,研究了拉伸保载时间对该钢低周疲劳行为的影响,并用扫描电镜对断口形貌进行了观察.结果表明：2．25Cr1MoV 钢呈明显的循环软化特性,拉伸保载会明显降低循环应力幅,但保载时间对循环应力幅的影响不大；拉伸保载使该钢的疲劳寿命降低,但保载时间超过60 s 后,疲劳寿命基本不受保载时间的影响；拉伸保载没有改变试验钢的疲劳断裂模式.%High temperature low cycle fatigue test was carried out on 2.25Cr1MoV steel by using a hydraulic fatigue testing system under strain-controlled mode at 455 ℃.Different tensile hold time (0,60,600 s)was imposed at peak strain to study the effect of tensile holding load time on low cycle fatigue behavior of the steel.The fracture morphology of the steel was observed by scanning electron microscopy.The results reveal that the steel showed cyclic softening characteristics.The applied tensile holding load caused the stress amplitude obviously reduced,but the holding load time had little effect on cyclic stress amplitude.The fatigue life of the steel decreased because of tensile holding,but the life changed little when holding time exceeded 60 s.The fracture mode was not changed by the tensile holding load.