Abstract: The fatigue crack initiation from notch root and the short-crack
growth laws of two medium carbon alloying structural
steels-35CrMo and 42CrMo are investigated under the different
stress ratios R=0.1,0.3 and three-point bending condition. The
relationships between the maximum stress range at the notch root Δσmax and the number of cycles before fatigue crack initiation
Ni and determined. The threshold stresses of fatigue crack
initiation (Δσmax)th are got, and the smallcrack growth laws are
obtained for these steels. An effective and convenient method is
proposed for predicting the fatigue life of the notch specimens.
Key words: Crack
initiation Crack propagation Short crack Fatigue life
Manuscript received on
September 2, 1997; revised manuscript March 15, 1998
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