Research on evolution behavior of 42CrMo microscopic fatigue short crack based on microstructure effect of material

To investigate the causes of damage dispersion in fatigue life of alloy materials, fatigue tests on 42CrMo are carried out under microscope with the aid of a micro fatigue testing device. The fatigue crack initiation and propagation evolution process of 42CrMo are studied on the micromechanical scale. The fatigue short crack and short crack growth rates are measured respectively under loads of 1400, 1550, and 1650 N. The experimental result shows that the initiation of fatigue short cracks is related to the randomness of microstructure defects. The initiation and propagation of fatigue short cracks on the surface of samples are random and local, while the propagation is characterized by first deceleration and then acceleration.