GH4710合金高温疲劳裂纹扩展行为与温度依赖模型研究

Temperature-Dependent Modeling of High-Temperature Fatigue Crack Growth Behavior in GH4710 Superalloy

摘要:

针对航空发动机GH4710合金涡轮盘的高温疲劳失效风险，系统研究了该合金在 750 ℃、815 ℃及 850 ℃下的疲劳裂纹扩展行为，揭示温度影响机制并建立温度依赖模型。结果表明，晶界氧化弱化是高温下裂纹加速扩展的主导因素，温度从750 ℃升至850 ℃时，合金疲劳裂纹扩展速率显著增大，疲劳寿命降幅达74.7%，断裂机制由穿晶主导向沿晶主导演变；815～850℃为疲劳性能临界突变温度范围，低于该温度时合金应力强度因子范围（ ΔK）更宽，抗裂纹扩展能力更优异。基于 Paris 公式引入Arrhenius 型温度修正项，建立模型：da/dN=9.783×10^(-7)×exp?(-3557.068/T) (ΔK)^3.183 （T 为绝对温度，K）。在ΔK =20~65 MPa?m0.5范围内，模型预测值与实验数据误差小于10%，可精准表征750~850℃区间合金的疲劳裂纹扩展行为，为GH4710合金涡轮盘的损伤容限设计、高温服役寿命预测及临界温度预警提供理论支撑。

Abstract:

Aiming at the high-temperature fatigue failure risk of GH4710 alloy turbine disks for aero-engines, the fatigue crack growth behavior of the alloy at 750℃, 815℃ and 850℃ was systematically studied, the temperature influence mechanism was revealed, and a temperature-dependent model was established. The results show that grain boundary oxidation weakening is the dominant factor for accelerated crack growth at high temperatures. When the temperature increases from 750℃ to 850℃, the fatigue crack growth rate of the alloy increases significantly, the fatigue life decreases by 74.7%, and the fracture mechanism transforms from transgranular dominance to intergranular dominance. The range of 815~850 ℃ is the critical mutation temperature range for fatigue performance, and below this temperature, the alloy has a wider stress intensity factor range ( ΔK) and better crack growth resistance. Based on the Paris equation, an Arrhenius-type temperature correction term was introduced to establish the model: da/dN=9.783×10^(-7)×exp?(-3557.068/T) (ΔK)^3.183 (T is absolute temperature, K). Within the range of ΔK =20~65 MPa·m?·?, the error between the model predictions and experimental data is less than 10%, which can accurately characterize the fatigue crack growth behavior of the alloy in the temperature range of 750~850℃. This study provides theoretical support for the damage tolerance design, high-temperature service life prediction and critical temperature early warning of GH4710 alloy turbine disks.