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研究了含0.34%Hf DD6单晶高温合金在760℃下的低周疲劳行为,对其疲劳裂纹的萌生与扩展进行了分析。结果表明,含0.34%Hf DD6合金比含0.10%Hf的疲劳寿命稍有降低;其损伤以弹性损伤为主。疲劳裂纹萌生于试样表面、亚表面或试样内部后,先沿垂直应力轴方向扩展,后沿{111}面扩展。其断裂机制为类解理断裂。断口上有典型的疲劳条带。断裂组织分析表明,位错主要在基体通道中扩展,变形后期切过γ’相,形成滑移带。
The low cycle fatigue behavior of a 0.34% Hf DD6 single crystal superalloy at 760 ℃ was investigated and the initiation and propagation of fatigue crack were analyzed. The results show that the fatigue life of the alloy containing 0.34% Hf DD6 is slightly lower than that of the alloy containing 0.10% Hf. The damage is mainly elastic. Fatigue crack initiation in the sample surface, subsurface or sample interior, the first along the vertical axis of stress expansion, the back along the {111} plane expansion. Its fracture mechanism is cleavage-like. Fracture typical fatigue band. Fracture analysis shows that the dislocations are mainly extended in the channel of the matrix, and the γ ’phase is cut at the late stage of deformation to form the slip band.