CF-8M铸造不锈钢主管道的热老化脆化行为研究  

Investigation on Thermal Aging Embrittlement Behavior of Primary Pipes in CF-8M Cast Stainless Steel

作　　者：吕云鹤 肖青山 马若群 陈银强 初起宝 LYU Yunhe;XIAO Qingshan;MA Ruoqun;CHEN Yinqiang;CHU Qibao(Nuclear and Radiation Safety Center,Ministry of Ecology and Environment,Beijing 100082,China;China Nuclear Power Operation Technology Co.,Ltd.,Wuhan 430223,China)

机构地区：[1]生态环境部核与辐射安全中心,北京100082 [2]中核武汉核电运行技术股份有限公司,湖北武汉430223

出　　处：《原子能科学技术》2023年第5期1016-1023,共8页Atomic Energy Science and Technology

基　　金：国家重点研发计划(2019YFB1900901)。

摘　　要：为了评价和预测铸造奥氏体不锈钢(CASS)材料服役期限内的热老化脆化程度,通过对美国的阿贡实验室(ANL)预测模型的研究和分析,以及在400℃下对核级CF-8M主管道材料实施了10 000 h的加速热老化试验,研究了CF-8M材料在不同热老化时间下拉伸性能、冲击性能和微观组织的变化规律,以冲击能作为表征热老化脆化程度的参数,获得了CF-8M材料的热老化脆化预测关系式,并与ANL模型的预测结果进行了对比和分析。结果表明,在加速热老化试验周期内随着热老化时间的增加,CF-8M材料的室温和高温(350℃)0.2%塑性延伸强度变化缓慢,抗拉强度缓慢增加;室温冲击能迅速下降,8 000 h以后冲击能下降趋势接近饱和状态;ANL模型对试验对象在加速老化试验周期内的冲击能预测结果不保守。CF-8M材料加速热老化10 000 h即等效服役30.49 a,其热老化脆化程度接近于热老化饱和状态。Cast austenitic stainless steel(CASS)materials have a duplex structure consisting of austenite and ferrite phases and are widely used in the manufacture of pressure boundary components for reactor coolant system.A large number of studies have shown that these material will undergo thermal aging embrittlement after long-term service at 290-320℃,resulting in a decrease in the fracture toughness of the material.However,as a key component in the reactor coolant system,the primary pipe is difficult to replace and has high replacement cost during its service period,which seriously restricts the operation safety and service life of nuclear power plants.Therefore,it is very important for the integrity of the reactor primary pressure boundary to evaluate and predict the thermal aging embrittlement of the primary pipe materials.In order to evaluate and predict the thermal aging embrittlement degree of CASS materials during their service life,through the research and analysis of the ANL prediction model and the accelerated thermal aging experiments of nuclear grade CF-8M static cast stainless steel primary pipe materials were carried out at 400℃for 10000 hours.The variations of tensile properties,impact energy and microstructure of stainless steel under different thermal aging time were studied.The impact energy was used as the characterization parameter of thermal aging,and the prediction formula of thermal aging embrittlement of stainless steel was obtained,which was compared with ANL model.The experimental results show that with the increase of thermal aging time,the 0.2%plastic elongation strength of stainless steel at room temperature and high temperature(350℃)varies slowly,and the tensile strength increases slowly during the accelerated thermal aging test cycle.In addition,it can be seen from the morphology of the expansion zone of the impact fracture that there are a large number of dimples in the expansion zone of the unaged sample.Although the dimples had different sizes,the overall dimples show the character

关 键 词：CF-8M铸造不锈钢 热老化脆化 拉伸性能 冲击韧性 预测 

分 类 号：TG142.71[一般工业技术—材料科学与工程]