Abstract: Crack propagation in 4-point bending impact fatigue and non-impact fatigue tests were studied using a few typical alloys. It has been found that there are three different types of relations between crack propagation in impact fatigue and that in non-impact fatigue. These relations are strongly associated with the micro-fracture mechanisms under impact and non-impact fatigue loads. The contradictory test results ottained by different authors in the past on the comparative study of crack propagation in impact fatigue and non-impact fatigue can thus be unified.

Key words: 冲击疲劳和非冲击疲劳, 裂纹扩展速率