700℃超超临界电站锅炉用高温合金617B和740H管道氩弧焊接头微观组织特征  

Microstructure Characteristics of 617B Tube and 740H Pipe TIG Welding Joints for 700 °C Ultra-supercritical Power Plant Boilers

作　　者：叶建水[1] 董建新[1] 张麦仓[1] 谢锡善[1] 

机构地区：[1]北京科技大学,北京100083

出　　处：《稀有金属材料与工程》2015年第9期2189-2195,共7页Rare Metal Materials and Engineering

基　　金：国家高技术研究发展计划("863"计划)(2012AA03A501)

摘　　要：采用光学显微镜、扫描电镜、显微硬度计等手段,研究了617B和740H管道氩弧焊接头微观组织和显微硬度。结果表明:617B焊件焊缝晶粒外延生长明显,焊缝主要存在Mo、Ti元素偏析,枝晶间分布着不连续颗粒状碳化物M6C,焊缝硬度略高于母材。740H焊件焊缝主要存在Nb、Ti元素偏析,枝晶间有较多不规则颗粒状碳化物MC,没有观察到γ-γ′共晶相;热影响区晶粒稍有长大,晶内强化相γ′减少,晶界碳化物M23C6和MC发生回溶,焊缝硬度明显低于母材。Microstructure and microhardness of 617 B tube and 740 H pipe TIG welding joints was studied by OM, SEM and HV tester. Results show that epitaxial growth of grains in FZ of 617 B weld is obvious, Mo and Ti are the principal segregated elements, and the interdendritic region consists of discontinuous second phase particle M6 C. The FZ hardness is slightly higher than that of BM. On the other hand, Nb and Ti are the principal segregated elements in FZ of 740 H weld and the interdendritic region consists of discrete irregular second phase particle MC. γ-γ′ eutectic microconstituents aren＇t observed. In HAZ, grains grow somewhat, while the total γ′ decrease. In addition, M23C6 and MC in HAZ grain boundary are dissolved to matrix. The FZ hardness is clearly lower than that of BM.

关 键 词：617B 740H 氩弧焊 微观组织 显微硬度 

分 类 号：TG407[金属学及工艺—焊接]