对汽轮机转子用2.25CrMoV钢在真空常温条件下进行高应力低周疲劳试验,对试样中起源于夹杂物和晶界等典型缺陷处的裂纹扩展进行了原位连续观测, 研究了典型缺陷对疲劳裂纹萌生和初期扩展的影响。结果表明: 在高应力循环载荷作用下, 夹杂物的形状和尺寸对疲劳裂纹的扩展无明显影响, 夹杂物处萌生裂纹的扩展速率小于晶界处萌生裂纹的扩展速率; 短裂纹群体效应和滑移线快速增殖的共同作用是导致试样疲劳破坏的主要原因。

High stress low cycle fatigue test was carried out on 2.25CrMoV steel used for rotor at vacuum and room temperature. Propagation of crack originate from typical defects such as inclusions and grain boundaries were continuous observed in-situ, the effects of typical defects on initiation and propagation of fatigue crack were studied. The results show that the shape and size of inclusions had no obvious influence on fatigue crack propagation under the high stress cyclic loading. The propagation rate of the crack initiated by inclusion was less than that of the crack initiated at grain boundary. The interaction between short crack group and the rapid increment of slip line was the main reasons of this sample destruction.