热老化对铸造奥氏体不锈钢的环境疲劳寿命影响  

Effect of Thermal Aging on Environmental Fatigue Life of Cast Austenitic Stainless Steel

作　　者：王仪美 肖青山 陈银强 刘廷光 WANG Yimei;XIAO Qingshan;CHEN Yinqiang;LIU Tingguang(China Nuclear Power Operation Technology Corporation,Ltd.,Wuhan 430223,China;University of Science and Technology Beijing,Beijng 100083,China)

机构地区：[1]中核武汉核电运行技术股份有限公司,湖北武汉430223 [2]北京科技大学,北京100083

出　　处：《原子能科学技术》2024年第8期1628-1634,共7页Atomic Energy Science and Technology

基　　金：国家重点研发计划(2019YFB1900905)。

摘　　要：铸造奥氏体不锈钢材料在一回路高温高压水环境下长期服役存在热老化和疲劳问题。本文对典型的核电厂主管道材料Z3CN20-09M开展400℃的加速热老化试验,利用透射电子显微镜分析热老化试样的结构,在高温空气和模拟一回路高温高压水环境下研究热老化后Z3CN20-09M的疲劳寿命变化规律,分析热老化时间对Z3CN20-09M疲劳寿命的影响。结果表明,Z3CN20-09M在热老化5 000 h后其(011)晶面上发生晶格畸变。随着热老化时间延长至5 000 h,Z3CN20-09M在高温空气和模拟一回路高温高压水环境下的疲劳寿命下降,ASME疲劳设计曲线对于评价Z3CN20-09M热老化后的疲劳寿命仍具有足够的安全裕量。Cast austenitic stainless steel(CASS)is widely used in the primary pipeline of pressurized water reactor nuclear power plants.Cast stainless steel will undergo thermal aging and embrittlement during long-term high-temperature service.CASS is actually composed of austenite and ferrite,and after long-term thermal aging,ferrite undergoes amplitude modulated decomposition,with the precipitation of G phase in the matrix.These are the main reasons for the embrittlement of CASS materials.During actual service,the main pipeline of the primary circuit not only bears the effects of long-term high-temperature thermal aging,but also bears the cyclic thermal and mechanical loads caused by startup and shutdown,reactor power fluctuations,and coolant flow,as well as the corrosion caused by the coolant of the primary circuit.These factors pose a risk of thermal aging and corrosion fatigue cracking in the main pipeline of the primary circuit.However,the impact of thermal aging on the performance of CASS mainly focuses on mechanical properties such as tension and impact,and there is relatively little research on the fatigue performance of CASS after thermal aging,especially in high-temperature and high-pressure water environments.Therefore,accelerated thermal aging tests were conducted at 400℃of different periods on a typical nuclear power plant main pipeline material Z3CN20-09M,and the structure of the thermal aging samples was analyzed using transmission electron microscopy in this study.The fatigue life changes of Z3CN20-09M after thermal aging were studied in high-temperature air of 300℃and simulated high-temperature and high-pressure water environment of the primary circuit to analyze the effect of thermal aging time on the fatigue behavior and life of Z3CN20-09M.The HRTEM results indicate that Z3CN20-09M undergoes lattice distortion on its(011)crystal plane after 5000 hours of thermal aging.No amplitude modulated decomposition products,namely Fe richαphase and Cr richα'phase,were found in Z3CN20-09M after 5000 hours of

关 键 词：铸造奥氏体不锈钢 热老化 铁素体 晶格畸变 环境疲劳 

分 类 号：TL1[核科学技术—核能科学] TG142.71[一般工业技术—材料科学与工程]