核电主管道铸造不锈钢的热老化脆化

Thermal aging embrittlement of cast stainless steel for nuclear primary pipes

为了研究中国核电主管道铸造不锈钢Z3CN20-09M的热老化,在300、350和400℃下,对Z3CN20-09M进行了长达30000 h的加速热老化实验.对不同热老化时间下的样品进行了冲击性能和铁素体纳米硬度测定.以夏比冲击功作为热老化脆化参量,利用拟合的方法得出该材料的热老化激活能为51.962 kJ·mol^(-1).通过热老化因子P得出了用夏比冲击功表示的热老化脆化动力学公式.利用热老化激活能和热老化动力学公式预测了Z3CN20-09M在实际运行温度下服役40 a内的夏比冲击功和铁素体显微硬度变化.预测结果表明在运行5 a内是该材料韧性迅速下降的时期,随后的运行过程中下降过程趋缓.

To study the thermal aging of the nuclear primary pipe material Z3CN20-09M, accelerated thermal aging experiments were performed at 300, 350 and 400 ℃ for 30000 h. Charpy impact energy and nanohardness of ferrite phase were tested for samples with different thermally aged time. Taking Charpy impact energy as the standard of thermal aging embrittlement, the thermal aging activation energy of the material was obtained to be 51.962 kJ·mo1-1 by the fitting method. Meanwhile, the thermal aging parameter P was used to describe the kinetics of thermal aging embrittlement with Charpy impact energy. Finally, the Charpy impact energy and nanohardness of the material during 40 operation years at the actual operation temperature were estimated by the thermal aging activation energy and the thermal aging kinetics. The predicted results show that the toughness of the material decreases fast in the early 5 years, and then undergoes a slowly-decreased operation process.