蒸汽发生器异种钢焊接接头疲劳裂纹扩展研究  

Research on Fatigue Crack Propagation of Welded Joints of Dissimilar Steel for Steam Generator

作　　者：徐连勇[1,2] 聂妙慧 赵雷 李丛[1,2] Xu Lianyong;Nie Miaohui;Zhao Lei;Li Cong(School of Materials Science and Engineering,Tianjin University,Tianjin 300350,China;Tianjin Key Laboratory of Advanced Joining Technology,Tianjin 300350,China)

机构地区：[1]天津大学材料科学与工程学院,天津300350 [2]天津市现代连接技术重点实验室,天津300350

出　　处：《天津大学学报（自然科学与工程技术版）》2024年第10期1044-1052,共9页Journal of Tianjin University：Science and Technology

基　　金：国家自然科学基金资助项目(52025052,52075374).

摘　　要：钠冷快堆是我国发展第4代先进核能系统的主力堆型,蒸汽发生器是钠冷快堆重要部件.为了保证蒸汽发生器的安全性和可靠性,对异种钢焊接接头进行疲劳裂纹扩展行为研究.异种钢焊接接头共有6个不同微区,分别为F22母材、F22侧热影响区、隔离层、堆焊层、对接焊缝及316H母材.对异种钢焊接接头进行硬度测试、显微组织观察、疲劳裂纹扩展试验,利用光学显微镜和扫描电子显微镜(SEM)进行微观组织观察.F22母材组织主要为铁素体、珠光体和贝氏体,F22侧热影响区组织主要为铁素体和珠光体,隔离层、堆焊层、对接焊缝主要组织为奥氏体和δ铁素体,316H母材组织主要为奥氏体.F22母材的显微硬度最小,隔离层显微硬度最大,堆焊层、对接焊缝、316H母材的显微硬度逐渐下降,F22侧热影响区显微硬度变化较大.在低ΔK时,F22母材的疲劳裂纹扩展速率最快,隔离层、堆焊层、对接焊缝、316H母材的疲劳裂纹扩展速率逐渐变缓,随着ΔK的增加,隔离层的疲劳裂纹扩展速率变化最快,这是因为隔离层裂纹逐渐向F22母材侧偏转,使得其抵抗疲劳裂纹扩展能力逐渐降低.δ铁素体会影响隔离层、堆焊层、对接焊缝的抗疲劳裂纹扩展能力.F22母材和F22侧热影响区的疲劳裂纹断口撕裂最严重,隔离层、堆焊层、对接焊缝的断口平坦度逐渐增加,316H母材的疲劳裂纹断口形貌最平坦,与抗疲劳性能相对应.Sodium-cooled fast reactor is the main reactor type for developing the fourth-generation advanced nuclear energy system in China.A steam generator is an essential component of sodium-cooled fast reactor.To ensure the safety and reliability of steam generator,the fatigue crack propagation behavior of dissimilar steel welded joints was investigated.Dissimilar steel welded joints have six microzones:F22 base metal,F22 side heat-affected zone,isolation layer,surfacing layer,butt weld,and 316H base metal.In this study,we performed hardness tests,microstructure observations,and fatigue crack propagation tests on the six microzones of a dissimilar steel welded joint.The microstructures were observed using an optical microscope and a scanning electron microscope(SEM).The structure of the F22 base metal was ferrite,pearlite,and bainite;the F22 side heat-affected zone was ferrite and pearlite;the isolation layer,surfacing layer,and butt weld were primarily austenite andδferrite;and 316H base metal was austenite.The microhardness of the F22 base metal was the smallest,and that of the isolation layer was the largest.The microhardness of the surfacing layer,butt weld,and 316H base metal gradually decreased,and that of the F22 side heat-affected zone rapidly changed.At lowK,the fatigue crack propagation rate of the F22 base metal was the fastest,and those of the isolation layer,surfacing layer,butt weld,and 316H base metal gradually slowed down.With an increase inK,the change in the fatigue crack propagation rate of the isolation layer was the most pronounced because its cracks gradually deflected to the side of the F22 base metal,gradually decreasing its resistance to fatigue crack propagation.δferrite could affect the antifatigue crack propagation ability of the isolation layer,surfacing layer,and butt weld.The fatigue crack fractures of the F22 base metal and F22 side heat-affected zone exhibited the most severe tear,and the fracture flatness of the isolation layer,surfacing layer,and butt weld gradually increased.In addi

关 键 词：异种钢 焊接接头 疲劳裂纹扩展 奥氏体 铁素体 

分 类 号：TG457.11[金属学及工艺—焊接]