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燃烧室火焰筒作为航空发动机的热端关键结构件,在工作过程中受到复杂的循环温度载荷,使其承受热疲劳损伤.对火焰筒常用镍基高温合金GH536的热疲劳行为进行试验研究.根据火焰筒结构和载荷特征,设计了中心孔平板试样以及热疲劳试验,研究了热疲劳载荷条件下GH536平板的裂纹萌生及扩展规律,揭示了GH536的热疲劳破坏机理.研究发现:(1)热疲劳裂纹以穿晶模式萌生,以沿晶方式扩展并断裂;(2)随着热疲劳试验中上限温度的升高,裂纹的萌生寿命缩短,裂纹扩展速率加快,试样在800℃时的热疲劳裂纹萌生寿命是900℃裂纹萌生寿命的4.5倍.
As a key component of the hot end of aeroengine, the combustion chamber flame tube is subjected to complex cyclic temperature loading during its working process, so that it can withstand the thermal fatigue damage.The thermal fatigue behavior of the nickel-based superalloy GH536, The structure of the flame tube and the load characteristics were studied. The center hole flat plate specimen and the thermal fatigue test were designed. The initiation and propagation of cracks in the GH536 plate under the thermal fatigue load were studied and the thermal fatigue failure mechanism of GH536 plate was revealed. (1) The thermal fatigue crack initiation occurs in the transgranular mode and extends and breaks along the intergranular mode. (2) With the increase of the maximum temperature in the thermal fatigue test, the initiation life of the crack is shortened and the crack growth rate is accelerated. Thermal fatigue crack initiation life is 900 times the crack initiation life of 4.5 times.