Turbine blades may suffer overheating and the resulting severe microstructural degradation or even premature failure during service. At present, the research on the effect of overheating on creep properties of directionally solidified superalloys is still very limited. In this study, directionally solidified superalloy DZ406 was subjected to overheating treatments at 1050 °C, 1150 °C, 1180 °C and 1220 °C for 30 min, and the corresponding stress rupture properties were tested under 980 °C/275 MPa. The results show that overheating resulted in the obvious dissolution of strengthening γ’ precipitates and γ/γ’ eutectic, for example the area fraction of γ’ precipitates decreased to 24.0% after overheating at 1220 °C, and was only about 1/3 of the initial value in the as-received microstructure. However, overheating has negligible influence on microstructural stability of carbides. Moreover, it is abnormal that the creep rupture properties of all samples after various overheating treatments were similar, and the creep voids were all located at the interfaces of MC carbides and γ matrix, and the alloy finally suffered interdendritic fracture. The main reason for this phenomenon is that the seriously degraded γ’ phase will recover before loading during the stress rupture tests, and its area fraction will basically return to the initial value, and thus leads to the recovery of the stress rupture property. Our results indicate that turbine blades will suffer obvious microstructural degradation during sudden short-term overheating, while this degradation may be restored in the subsequent normal service process, overheating does not necessarily lead to the damage of blade performance.

涡轮叶片可能会过热，并导致严重的微观结构退化，甚至在使用期间过早失效。目前，关于过热对定向凝固高温合金蠕变性能影响的研究仍然非常有限。在这项研究中，定向凝固的高温合金DZ406在1050°C，1150°C，1180°C和1220°C进行了30分钟的过热处理，并在980°C / 275 MPa下测试了相应的应力断裂性能。结果表明，过热导致强化的γ'析出物和γ/γ'共晶的溶解明显消失，例如，γ'析出物的面积分数在1220°C过热后降低至24.0％，仅为1/3左右。初始结构的初始值。然而，过热对碳化物的微观结构稳定性的影响可忽略不计。而且，所有样品经过各种过热处理后的蠕变断裂特性都相似，并且蠕变空隙都位于MC碳化物和γ基体的界面，合金最终出现了枝晶间断裂，这是异常的。产生这种现象的主要原因是，在应力断裂试验中，严重降解的γ'相将在加载前恢复，其面积分数基本恢复到初始值，从而导致应力断裂性能的恢复。我们的结果表明，涡轮叶片会在突然的短期过热中遭受明显的微观结构退化，而这种退化可能会在随后的正常使用过程中得以恢复，