GH3230合金焊接薄板用于制造先进航空发动机的热端部件，焊接接头组织稳定性与发动机的安全性及可靠性紧密相关。为阐明不同服役条件下焊接接头显微组织的变化规律，本工作研究了GH3230合金薄板填丝钨极氩弧焊接头经不同高温(700~1000 ℃)长期热暴露处理后的显微组织以及碳化物的演变。结果表明，不同温度热暴露2000 h后，焊缝区树枝晶形貌消失，枝晶偏析程度显著降低，热影响区晶粒尺寸不均匀，晶粒内及晶界碳化物析出明显增多。不同温度长期热暴露后焊接接头中的2类碳化物(Cr, W)₂₃C₆和(W, Cr)₆C中合金元素的固溶度和含量发生变化，M₂₃C₆型碳化物粗化速率明显增大。GH3230合金氩弧焊接薄板在长期热暴露中，焊接接头内发生了碳化物类型、数量、尺寸、形貌和位置分布变化及碳化物间的退化反应。

GH3230 superalloy has excellent high-temperature mechanical properties and oxidation resistance; hence, it is widely used to manufacture key high-temperature structural components in the aerospace and other fields. In the research, development and production process of aero-engines and gas turbines, GH3230 superalloy plate is often used to make the welded components of a combustion chamber. Excellent weldability is an important technical index and is also an important basis for the plate component design and welding process formulation. For GH3230 superalloy welded plates used at high temperature, the stability of the microstructure of the welded joint is closely related to the mechanical properties of welded components. However, in theory, some deficits remain in the in-depth study of scientific problems regarding GH3230 superalloy welding; hence, the microstructure evolution of welded joint during its long-term service at high temperature has attracted attention. This study focuses on observing and analyzing the experimental phenomena of microstructural changes in welded joint (in the weld and heat affected zones), changes in the alloy element content of carbides, the coarsening rate of carbides, and degradation reaction between carbides after long-term thermal exposure at various high temperatures. Experimental results show that in the tungsten argon-arc welded thin plate of GH3230 superalloy, the dendrite morphology of the weld zone disappears after 2000 h of thermal exposure. Furthermore, the degree of dendrite segregation decreases remarkably, grain size in the heat affected zone becomes uneven, and carbide precipitation in the grain and grain boundary increases obviously. After long-term thermal exposure at various temperatures, the solid solubility and content of alloying elements in two types of carbides—(Cr, W)₂₃C₆ and (W, Cr)₆C—in the welded joint change and coarsening rate of M₂₃C₆ carbide exhibits an obvious increase. During the long-term thermal exposure of the argon-arc welded thin plate, the microstructures of the weld and heat affected zones undergo alloy carbide degradation based on diffusion, which changes the type, quantity, size, morphology, and location distribution of carbide.