Effect Mechanism of Different Dust Particles on Fatigue Crack Growth Behavior of 7N01-T6 Aluminum Alloy

The influence mechanism of different dust (road-dust and coal-dust) particles on the fatigue crack growth behavior of 7N01-T6 aluminum alloy was studied by fatigue crack growth test, scanning electron microscope quasi in-situ observation. The results show that during crack growth stage at stress ratio of 0.1 and stress intensity factor range less than 18 MPa·m^1/2, the fatigue crack growth rate of aluminum alloy under road-dust or coal-dust particle environment was obviously smaller than that under air environment, and the crack growth rate under coal-dust particle environment was the smallest; this was because the size of coal-dust particles was obviously larger than that of road-dust particles and the crack closure effect was aggravated. With increasing stress ratio to 0.5, the difference between the fatigue crack growth rate in the dust particle environment and that in the air environment decreased, which was related to the weakening of crack closure effect with increasing stress ratio. Dust particles increased the crack closing gap, promoted the crack closing effect, and led to a large number of slip bands and microcracks at the crack tip, which greatly consumed the energy of crack growth and reduced the crack growth rate.