高Cr铁素体耐热钢与奥氏体耐热钢的异种材料扩散连接接头组织演变及力学性能  

Microstructure Evolution and Mechanical Properties of Dissimilar Material Diffusion-Bonded Joint for High Cr Ferrite Heat-Resistant Steel and Austenitic Heat-Resistant Steel

作　　者：化雨 陈建国 余黎明[1] 司永宏 刘晨曦[1] 李会军[1] 刘永长[1] HUA Yu;CHEN Jianguo;YU Liming;SI Yonghong;LIU Chenxi;LI Huijun;LIU Yongchang(State Key Laboratory of Hydraulic Engineering Simulation and Safety,School of Materials Science and Engineering,Tianjin University,Tianjin 300354,China;Tianjin Special Equipment Inspection Institute,Tianjin 300192,China)

机构地区：[1]天津大学材料科学与工程学院水利安全与仿真国家重点实验室,天津300354 [2]天津市特种设备监督检验技术研究院,天津300192

出　　处：《金属学报》2022年第2期141-154,共14页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目Nos.52034004和51975404;天津市自然科学基金项目Nos.18JCQNJC03300和18YFZCGX00050。

摘　　要：开展了高Cr铁素体耐热钢与TP347H奥氏体耐热钢的异种材料真空扩散连接实验,研究了扩散连接时间及焊后热处理工艺对扩散影响区组织演变和力学性能的影响。结果表明,随着扩散连接时间的延长,界面结合率逐渐增加。变形储存能差异与位错滑移的相互作用下,在扩散连接界面处发生动态再结晶形成了细小晶粒,最终演化成锯齿状的界面结合形态。扩散连接区晶界与晶粒内部析出细小弥散的MX、M23C6相。焊后热处理之后扩散连接区的晶粒进一步细化,位错相对稳定化,位错密度减少,小角度晶界增多,元素扩散更加充分。对获得的扩散连接试样进行不同温度的拉伸实验,断裂位置均位于基体中,说明获得了高质量的异种材料扩散连接接头。High Cr ferrite heat-resistant steel has excellent geometric structure stability,low radiation swelling rate,and good corrosion resistance of liquid metal.TP347H austenitic heat-resistant steel is based on the traditional 18-8 austenitic steel with the addition of a certain amount of Nb and a small amount of N to precipitate MX-type carbonitride,which results in superior high-temperature properties.Steam with high temperature and pressure flowing through supercritical thermal power units may exhibit heterogeneous connections between high Cr ferrite and austenitic heat-resistant steel components in the supercritical thermal power units.In this study,the vacuum diffusion-bonding of dissimilar materials between high Cr ferritic and TP347H austenitic heat-resistant steel was performed,the effects of diffusionbonding time and post weld heat treatment(PWHT)process on the microstructural evolution and mechanical properties of the diffusion-affected zone was examined.The results indicated that with the extension of diffusion-bonding time,the interfacial bonding rate gradually increased.The interaction due to the difference in deformation storage energy and dislocation slips resulted in dynamic recrystallization,and the fine grains formed at the diffusion-bonding interface evolved into a serrated interface.Fine and dispersed MX and M23C6 phases were precipitated in the austenite grain boundaries and at the grain boundaries of the diffusion-bonding zone.After PWHT,the grains in the diffusion-bonding zone were further refined,dislocations were stable,dislocation density reduced,small-angle grain boundaries increased,and element diffusion was more sufficient.Tensile tests at different temperatures showed that the fractured sites were all in the matrix,which indicates that high-quality diffusion-bonding joints of dissimilar materials were achieved.

关 键 词：高Cr铁素体耐热钢 TP347H奥氏体耐热钢 扩散连接 显微组织 力学性能 

分 类 号：TG457.1[金属学及工艺—焊接]