Abstract
The 2524-T3 aluminum alloy was subjected to fatigue tests under the conditions of R = 0, 3.5% NaCl corrosion solution, and the loading cycles of 106, and the S-N curve was obtained. The horizontal fatigue limit was 169 MPa, which is slightly higher than the longitudinal fatigue limit of 163 MPa. In addition, detailed microstructural analysis of the micro-morphological fatigue failure features was carried out. The influence mechanism of corrosion on the fatigue crack propagation of 2524-T3 aluminum alloy was discussed. The fatigue source characterized by cleavage and fracture mainly comes from corrosion pits, whose expansion direction is perpendicular to the principal stress direction. The stable propagation zone is characterized by strip fractures. The main feature of the fracture in the fracture zone is equiaxed dimples. The larger dimples are mixed with second-phase particles ranging in size from 1 to 5 μm. There is almost a one-to-one correspondence between the dimples and the second-phase particles. The fracture mechanism of 2524 alloy at this stage is transformed into a micro-holes connection mechanism, and the nucleation of micropores is mainly derived from the second-phase particles.
Highlights
2524-T3 aluminum alloy has the advantages of low density, high specific strength, excellent corrosion resistance, good formability, and low cost, so it is the main material in aircraft, vehicles, bridges, engineering equipment, and large pressure vessels [1,2,3]
The horizontal fatigue corrosion performance is slightly better than the performance of longitudinal corrosion
In the morphology of the fatigue fracture, the crack closure of the fatigue source region is mainly affected by the roughness
Summary
2524-T3 aluminum alloy has the advantages of low density, high specific strength, excellent corrosion resistance, good formability, and low cost, so it is the main material in aircraft, vehicles, bridges, engineering equipment, and large pressure vessels [1,2,3]. Corrosion fatigue is not a simple superposition of corrosion and fatigue damage but rather a process of synergy and promotion It has great destructive effects on the aluminum alloy structure [7,9]. R.K. et al [16] studied the effects of corrosion on mechanical properties and fatigue life of 8011 aluminum alloy. Grain sizes among 50 and 100 mm exhibited high fatigue crack propagation resistances When it comes to the effect of localized corrosion environment on fatigue properties of aluminum alloys, the studies reported recently [18,19,20,21] put their stress on the action of corrosion environment, especially the electrochemical effect on the fatigue life and properties. By measuring the length of the crack and observing the width of the fatigue striations at different stages, the change in the crack growth rate is explained
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