固溶热处理对新型核用FeCrAl合金包壳管组织和力学性能的影响  

Microstructure and Mechanical Properties of a New Nuclear FeCrAl Alloy Cladding Tubes with Solution Heat Treatment

作　　者：靳舜尧[1] 黄重国[1] 李升 Jin Shunyao;Huang Zhongguo;Li Sheng(School of Mechanical Engineering,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学机械工程学院,北京100083

出　　处：《稀有金属》2021年第1期10-18,共9页Chinese Journal of Rare Metals

基　　金：中央高校基本科研业务费专项资金项目(FRF-TP-19-013A2)资助。

摘　　要：通过新型核用锻态FeCrAl合金包壳管在不同温度及时间下的固溶处理实验,利用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射(XRD)、维氏硬度仪(HV)和电子万能试验机(EUTM)分析了固溶处理对FeCrAl合金包壳管显微组织以及力学性能的影响规律。结果表明,当固溶热处理温度低于1200℃时,保温60 min后FeCrAl合金组织中仍然存在一定数量的σ-FeCr相、富Cr相和Fe_(2)(Mo/Nb)Laves析出相。随着温度的升高,析出相逐渐溶解到基体之中,当温度升高到1200℃时,保温60 min后组织内的析出相基本回溶,但晶粒发生了异常长大。随着保温时间的不同,析出相的数量、形态、分布和成分都会发生变化。随着温度的升高,FeCrAl合金的抗拉强度逐渐降低,延伸率先升高再降低,硬度先减小再增大。在1150℃加热、60 min保温和水冷的固溶热处理制度下,核用FeCrAl合金包壳管的伸长率可达20.1%,抗拉强度R_(m)为675 MPa,屈服强度R_(p0.2)为560 MPa,硬度为HV 261,塑性提高,加工性得到显著改善,可满足管材后续轧制的要求。Nuclear fuel cladding tube is the first line for nuclear power plant safety.It is an important component to ensure the safe andnormal operation of nuclear power plants and prevent nuclear fuel leakage under accidents.In recent years,it has been found that Fe-CrAl alloy has excellent resistance to high temperature oxidation,radiation,corrosion and excellent comprehensive mechanical proper-ties,and is expected to become the next generation of accident-resistant fuel cladding substitute materials.However,the addition ofmultiple elements produced more insoluble precipitated compounds in the FeCrAl alloy,resulting in high strength and low plasticity ofthe forged FeCrAl alloy during cold rolling.By studying the effect of solution heat treatment on the microstructure and mechanical prop-erties of forged tube blanks,a suitable solution heat treatment was finally determined to improve the workability of FeCrAl alloy.First-ly,the FeCrAl alloy samples were processed with different solution heat treatment using box-type resistance furnace.Then the sampleswere mechanically polished and corroded with a mixed solution of HCl(25%)+HNO_(3)(25%)+H_(2)O(50%).The microstructure was ob-served by metallography(OM)and scanning electron microscope(SEM).The microhardness was measured using a Vickers hardnesstester(HV).Tensile performance was tested using electronic universal testing machine(EUTM).The mainly types of the precipitateswere observed using SEM and X-ray diffraction(XRD).When the solution heat treatment temperature was below 1200℃,a certainamount ofσ-Fe Cr phase,Cr-rich phase and Fe_(2)(Mo/Nb)Laves phase still existed in the FeCrAl alloy.The precipitates gradually dis-solved into the matrix with the increasing temperature.The precipitated phase dissolved into matrix at 1200℃,but the grains grew ab-normally.The types of precipitates in FeCrAl alloys changed with the solution heat treatment temperature.The precipitated phases inthe forged FeCrAl alloy and solution heat treatmented at 1050℃were mainly Fe_(2)M(M=Mo,Nb)(hP12

关 键 词：核用FeCrAl合金 包壳管 固溶热处理 显微组织 力学性能 

分 类 号：TL344[核科学技术—核技术及应用]