Pressurized piping systems in nuclear power plants made of cast duplex stainless steels (CDSSs) are subjected to thermal aging and fatigue. Low cycle fatigue tests on a nuclear grade CDSS revealed prolonged fatigue lives after thermal aging at 400 °C up to 10000 h. The underlying mechanism is mainly associated with the reduced plastic strain amplitude, which is presumably a result of thermal aging induced ferrite embrittlement and strengthening of austenite. A life prediction model was proposed with austenite microhardness incorporated into the Basquin-Coffin-Manson equation as a variable to reflect the effect of thermal aging.

中文翻译：

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铸造双相不锈钢热时效后的疲劳失效机理及寿命预测

铸铁双相不锈钢（CDSS）制成的核电站中的加压管道系统会遭受热老化和疲劳。在核级CDSS上进行的低周疲劳测试表明，在400°C达10000 h的热老化后，疲劳寿命延长。潜在的机理主要与塑性应变幅度减小有关，塑性应变幅度减小可能是由于热时效引起的铁素体脆化和奥氏体强化的结果。提出了寿命预测模型，将奥氏体显微硬度纳入Basquin-Coffin-Manson方程作为变量，以反映热老化的影响。