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由于高的热效率和简单的系统组成,超临界水堆已经被选为第4代反应堆概念机组。实现超临界水堆的关键之一是重要部件尤其是燃料组件包壳材料的高温力学性能。该文以镍基合金C276为研究对象,对其进行应变控制下具有保持时间的高温低周疲劳实验研究。实验温度为650℃,对称梯形波,最大拉压应变保持时间分别为0,30s和60s,应变范围均为±0.3%～±0.5%。对镍基合金C276在有应变保持情况下的循环应力特征、应力松弛规律、控制应变与循环应力的关系、应变与寿命的关系进行了分析。实验结果表明:Ni基合金C276为循环硬化材料,应变保持强化了循环硬化效应;给出了有保持情况下的频率修正循环应力-应变关系公式和有应变保持的频率修正应变-寿命公式。
Supercritical water reactors have been selected as Generation 4 reactor concept units due to their high thermal efficiency and simple system composition. One of the keys to achieving a supercritical water reactor is the high-temperature mechanical properties of critical components, especially fuel cladding materials. In this paper, Ni-based alloy C276 is taken as the research object, which is subjected to high temperature and low cycle fatigue test with holding time under strain control. The experimental temperature is 650 ℃, symmetrical trapezoidal wave, the maximum tensile and compressive strain retention time is 0,30 s and 60 s respectively, the strain range is ± 0.3% ~ ± 0.5%. The relationship between the cyclic stress characteristics, the stress relaxation law, the relationship between the control strain and cyclic stress, the strain and the life time of the nickel-based alloy C276 under the condition of strain preservation was analyzed. The experimental results show that the Ni-based alloy C276 is a cyclic hardened material, and the strain hardening enhances the effect of cyclic hardening. The frequency-corrected cyclic stress-strain equation and strain-retained frequency-corrected strain-life formula with retention are given.