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测试了国产第三代核电站一回路主管道材料-316LN不锈钢的室温低周疲劳性能,讨论了微观机理并建立了Manson-Coffin疲劳寿命模型。结果表明,随着应变幅的增大,滞回曲线宽度及峰值应力随之增大,疲劳过程中先后发生了循环硬化、快速循环软化、慢速软化和失稳四个变形阶段;应变幅由0.2%逐渐增加至1.2%的过程中,疲劳周次从105逐渐降低至102;疲劳断口由裂纹源区、扩展区和最终断裂区组成,疲劳裂纹主要萌生于表面,裂纹区具有典型的疲劳辉纹形貌,最终断裂区具有韧窝形貌。
The room temperature low cycle fatigue properties of 316LN stainless steel, the main material of the first-generation nuclear power plant in China, were tested. The microscopic mechanism was discussed and the Manson-Coffin fatigue life model was established. The results show that with the increase of strain amplitude, the width of hysteresis curve and the peak stress increase. There are four deformation phases of cyclic hardening, rapid cyclic softening, slow softening and instability successively in the fatigue process. The fatigue cycle gradually decreased from 105 to 102; the fatigue fracture consisted of the crack source zone, extension zone and final fracture zone, the fatigue crack mainly appeared on the surface and the crack zone had the typical fatigue Pattern morphology, the final fracture zone has dimple morphology.