GH3535高温合金的蠕变断裂机理和寿命预测  

Creep fracture mechanism and life prediction of GH3535 superalloy

作　　者：张建雄 王晚霞[2] 樊光程 贾彦彦[2] 龚永勇[1,4] 陆燕玲[2,3] ZHANG Jianxiong;WANG Wanxia;FAN Guangcheng;JIA Yanyan;GONG Yongyong;LU Yanling(College of Sciences,Shanghai University,Shanghai 200444,China;Shanghai Institute of Applied Physics,Chinese Academy of Science,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China;Advanced Solidification Technology Center,Shanghai University,Shanghai 200444,China)

机构地区：[1]上海大学理学院,上海200444 [2]中国科学院上海应用物理研究所,上海201800 [3]中国科学院大学,北京100049 [4]上海大学先进凝固技术中心,上海200444

出　　处：《钢铁》2023年第12期137-145,155,共10页Iron and Steel

基　　金：国家自然科学基金资助项目(52071330,52071194);上海市科技创新行动计划资助项目(19DZ2200300);中科院战略先导科技专项资助项目(XDA02004210)。

摘　　要：钍基熔盐堆中构件与高温熔融的氟化盐、核燃料及其裂变产物直接接触,这导致材料要同时处于高温、受力、强中子辐照和强熔盐腐蚀等交互作用的多重极端环境中。GH3535合金作为熔盐堆构件的候选材料之一,其力学性能的研究对熔盐堆的设计和安全性评估具有重要意义。以GH3535高温合金为研究对象,开展了650、700、750、800℃不同应力条件下的蠕变试验,采用SEM、EDS、EPMA等表征方法分析了合金微观组织与蠕变断裂机理。结果表明,GH3535合金在650℃时,其断裂方式为沿晶断裂,随着温度的升高,该合金的断裂方式由沿晶断裂转变为韧性断裂。GH3535合金一次析出相富含Mo、Si和C元素,其既存在于晶界又存在于晶内,蠕变过程中有二次析出相在晶界处析出。蠕变裂纹起源于晶界交汇处,裂纹处存在C元素富集。利用蠕变试验数据,建立了GH3535合金的Norton蠕变模型,获得了同一温度下的蠕变速率与应力关系式,得到了GH3535合金的蠕变极限。在此基础上,建立了基于时间温度参数法的Larson-Miller(LM)模型和基于蠕变曲线的修正θ参数模型。相比于LM模型,修正θ参数法可以充分利用蠕变曲线信息,具有更高的预测精度和更好的实用价值。Components in Thorium molten salt reactors are in direct contact with high-temperature molten fluorides,nuclear fuel,and its fission products.This necessitates that the materials simultaneously withstand extreme conditions,including high temperatures,stress,intense neutron irradiation,and corrosive molten salt environments.GH3535 superalloy is one of the candidate materials for molten salt reactor components,and studying its mechanical properties is of significant importance for design and safety assessments.In this study,GH3535 superalloy was selected as the research subject,and creep tests were conducted under different stress conditions at 650,700,750,and 800℃.Microstructure and creep fracture mechanism were analyzed by SEM,EDS and EPMA methods.The results showed that the fracture mode of the GH3535 superalloy at 650℃is intergranular fracture.With increasing of the temperature,fracture mode of the alloy could change from intergranular fracture to ductile fracture.The alloy exhibits primary precipitation phases rich in Mo,Si,and C elements,which exist both at grain boundaries and within grains.Secondary precipitation phases are observed to precipitate at grain boundaries during the creep process.cracks initiate at the intersection of grain boundaries,where there is an enrichment of C elements.Utilizing the creep test data,a Norton model was established to obtain the relationship between creep rate and stress at the same temperature,thus determining the creep limit of GH3535 alloy.Additionally,Larson-Miller(LM)model based on time-temperature parameter method and modifiedθparameter model based on creep curve have been established.Compared with the LM model,the modifiedθparameter method fully utilizes information of the creep curve,which has higher prediction accuracy and better practical value.

关 键 词：GH3535合金 蠕变性能 断裂机理 寿命预测 修正θ法 

分 类 号：TG132.3[一般工业技术—材料科学与工程]