中文摘要：

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。

英文摘要：

Supercritical water reactor （SCWR） has been selected as a kind of concept unit of Generation IV for its high thermal efficiency and simple system composition.One of the keys to implement SCWR is materials＇ high temperature mechanical properties of the core components,especially the fuel cladding.This paper presented the results of the strain-controlled high temperature low cycle fatigue experiment of hastelloy C276.Test was carried out at 650℃,symmetrical trapezoid strain waveform.The holding time at both maximum tensile and compression was 0,30 and 60 s,respectively.Strain range was from ±0.3% to ±0.5%.Cyclic stress characters,stress relaxation charters during time holding,and relations of both controlled strain vs cyclic stress and strain vs cycles to failure were investigated.The results show that Ni-based hastelloy C276 is cyclic hardening material,and strain holding intensifies the harden effect.The formula of cyclic stress vs strain and strain vs life to failure with frequency modification are obtained.