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研究了同成分合金在定向凝固（ＤＳ）和普通铸造（ＣＣ）状态下７６０℃的低周疲劳性能。结果表明，ＤＳ合金的疲劳寿命比ＣＣ合金在应力控制条件下高２倍左右，而在应变控制条件下可提高寿命２０倍左右。ＣＣ合金的疲劳裂纹往往萌生在与表面相连的晶界或某些缺陷（如孔洞）上，由外向内沿晶界扩展。而ＤＳ合金裂纹则起源于纵向晶界的横段或预开裂的碳化物，并沿枝晶间穿枝干扩展。
The low cycle fatigue behavior of the same composition alloy at 760 ℃ under directional solidification (DS) and normal casting (CC) conditions was investigated. The results show that the fatigue life of DS alloy is about 2 times higher than that of CC alloy under stress control and about 20 times longer under the strain control condition. The fatigue cracks of CC alloy often occur on the grain boundaries or some defects (such as holes) connected with the surface, and extend from the outside to the inside along the grain boundaries. The DS alloy cracks originated in the longitudinal grain boundaries of the cross-section or pre-cracking carbides, and along the interdendritic intergranular expansion.