核电站主管道材料长期热老化与研究.pdfVIP

（9 ）材料设计、性能表征与服役行为 核电站主管道材料的长期热老化研究 1 1 1 1 2 2 李时磊 ，李树肖 ，王西涛 ，王艳丽 ，薛飞 ，束国刚 （1. 北京科技大学新金属材料国家重点实验室，北京 100083； 2. 中国广东核电集团，广东省深圳市 215004 ） 摘 要：本文对取自某核电站的主管道材料进行了400 °C 长达20000 h 的长期热老化处理，研究了热 老化过程中材料力学性能和微观组织的变化规律。仪器化冲击实验结果表明，材料的冲击韧性随着热老化 时间的延长不断下降，冲击功的损失主要发生在热老化的前期。长期热老化处理后，材料的夏比冲击功下 降到很低的水平，断口形貌表现为典型的脆性断口。纳米力学探针研究表明，随热老化时间的延长，铁素 体的硬度逐渐增加，而塑性不断下降。透射电镜对铁素体相的观察表明，铁素体相在长期老化后析出了弥 散的小颗粒，这是导致铸造奥氏体不锈钢热老化的主要原因。 关键词：金属材料；主管道材料；铸造奥氏体不锈钢；热老化；夏比冲击 Study of long-term thermal aging in primary circuit piping materials of nuclear power plant 1 1 1 1 2 LI Shilei ，LI Shuxiao ，WANG Xitao ，WANG Yanli ， XUE Fei ，SHU Guogang2 1. State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083； 2. China Guangdong Nuclear Power Group, Shenzhen, Guangdong 215004 Abstract：The Z3CN20-09M stainless steel cut from the primary piping of a nuclear power plant was aged as long as 20000 h at 400 °C, and the change of the aged materials’mechanical properties was investigated. Instrumented impact test results showed that the materials’impact toughness declined with aging time and the main part of loss in impact energy occurred in the early stage of thermal aging. Reduction of unstable crack formation energy was the main effect of thermal aging on the materials’impact fracture energy . After aged for 20000 h, Charpy impact energy decreased to a very low level and fracture morphologies changed from ductile to brittle. Changes in ferrite led to a degradation of the mechanical properties. Nano-indentation tests indicated that the hardness in ferrite increased but ferrite ’s plastic deformation ability reduced with aging time. Large number of particles precipitated homogeneously in ferrite of aged materials. The precipitation in ferrite was considered to the primary mechanism of thermal agin g in CASS at mid- temperature.. Key words ：metal mater