ABSTRACT Since the preliminary data suggest that Fe-25Ni-20Cr austenitic stainless steel (Alloy 709) is an excellent candidate as a structural material for high-temperature applications such as Sodium-cooled Fast Reactor (SFR), the effect of strain range on creep-fatigue interaction of the Alloy 709 is investigated by conducting strain-controlled creep-fatigue tests with tensile hold times of 0, 600, 1,800 and 3,600 s at strain ranges varying from 0.6% to 1.2% at 750°C and 2 × 10−3 s−1 strain rate. Strain-controlled fatigue tests were performed at strain ranges from 0.3% to 2.5% at 750°C and 2 × 10−3 s−1 strain rate. The predicted fatigue life of Alloy 709 shows a better correlation with the characteristic slopes predictive method. With increasing strain range at a given hold time, the number of failure cycles decreases until saturation. The fractography of the deformed samples exhibited increased number of cracks with strain range along with M23C6 precipitates and high dislocation density.

中文翻译：

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应变范围对 Fe-25Ni-20Cr (wt.%) 奥氏体不锈钢（合金 709）高温蠕变疲劳行为的影响

摘要 由于初步数据表明 Fe-25Ni-20Cr 奥氏体不锈钢（合金 709）是钠冷快堆 (SFR) 等高温应用的结构材料，应变范围对蠕变的影响- 709 合金的疲劳相互作用通过进行应变控制蠕变疲劳试验来研究，拉伸保持时间为 0、600、1,800 和 3,600 秒，应变范围从 0.6% 到 1.2%，在 750°C 和 2 × 10− 3 s-1 应变率。应变控制疲劳试验是在 0.3% 到 2.5% 的应变范围内在 750°C 和 2 × 10-3 s-1 应变速率下进行的。合金 709 的预测疲劳寿命与特征斜率预测方法具有更好的相关性。在给定的保持时间，随着应变范围的增加，失效周期数会减少直到饱和。