K 4169合金铸件的常温疲劳断裂行为

摘要：
通过在某K4169合金精密大型熔模铸件本体典型承力结构处取样而进行常温疲劳试验，并结合疲劳断口的分析与凝固过程的温度场模拟，对其疲劳断裂机制进行探讨.结果表明，不同结构试样的疲劳寿命差异显著，其疲劳失效与微观疏松缺陷及其分布有关.早期的疲劳失效试样中存在大量的疏松缺陷，而疲劳性能较好的试样的疏松缺陷很少.当疏松缺陷较少时，疲劳裂纹主要沿晶间Laves相和碳化物扩展；当疏松缺陷较多时，裂纹主要经疏松缺陷而加速扩展并导致试样的早期失效.
关键词：
K4169合金； 疲劳断裂； 疏松缺陷； 模拟
中图分类号： TG 111.8
文献标志码： A

Fatigue Fracture Behavior of K4169 Alloy Casting at Room Temperature

The fatigue properties of the specimens cutting from the characteristic structure of the K4169 heavy investment casting were tested at room temperature. The mechanism of fatigue fracture was studied by combinational fracture analysis and temperature field simulation of solidification process. The results reveal that the structure of the casting has significant influence on the fatigue life. The fatigue failure of specimens is related to the content and distribution of the microporosity. A less microporosity leads to a well fatigue performance, and vice versa. The fatigue crack propagates along the interdentric Laves phase and carbide with low content of microporosity. However, the crack mainly accelerates through microporosity capturing with high content of microporosity, which leads to earlier failure of the specimen.