通过高周疲劳性能测试和组织形貌观察, 研究了K416B镍基高温合金700 ℃的高周疲劳行为. 结果表明, 在700 ℃和应力比R=-1条件下, 合金疲劳寿命随着应力的升高而减小, 高周疲劳强度为175 MPa; 在低应力条件下, 形变位错在γ基体中发生不同取向滑移, 随着应力增加, 位错剪切γ'相, 形成层错; 在拉压高周疲劳期间, 合金中开动多个滑移系, 并沿不同方向发生扭曲变形, 在γ +γ'共晶及碳化物附近产生应力集中, 致使裂纹源萌生于合金表面附近的共晶及块状碳化物处. 随着高周疲劳进行, 裂纹在扩展区沿枝晶间扩展, 并在瞬断区发生典型的解理断裂.

Ni-based speralloys have been widely used to make the blade parts of the advanced aeroengines for their high temperature tolerance and good mechanical property. During high temperature service, the materials endure the effects of temperature and alternating load, causing high-cycle fatigue deformation on the hot-end components. Meanwhile, the fatigue behaviors of the alloy are closely related to the deformation mechanisms and its microstructure characteristics, such as the size, distribution and morphology of γ' phase and carbides, and the fatigue fracture of the using materials possesses unpredictability. Therefore, investigating fatigue behaviors of the material is of significance in alloy design and life prediction. But the high-cycle fatigue behavior of K416B superalloy with high W content is still unclear up to now. For this reason, by means of high-cycle fatigue property measurement and microstructure observation, the high-cycle fatigue behavior of K416B Ni-based superalloy at 700 ℃ has been investigated. The results show that at 700 ℃ and stress ratio R=-1, the high-cycle fatigue life of K416B superalloy decreases with the stress increasing, and high-cycle fatigue strength of the alloy is 175 MPa. At the condition of low stress amplitude, the deformed dislocations may slip along different orientations in the matrix. With the stress amplitude increasing, the dislocations may shear into γ' phase and form the stacking fault. During tension and compression high-cycle fatigue, multiple slip systems are activated in the alloy, and the distortion occurs along various directions, resulting in stress concentration on the regions of γ +γ' eutectic and carbides. The crack sources may be initiated at the eutectic and blocky carbide near the surface of the alloy. As high-cycle fatigue goes on, the cracks propagate along the inter-dendrite in expansion region, and the typical cleavage fracture occurs in the final rupture region.