The Effects of Corrosion and Cathodic Charging on Fatigue Crack Propagation in 7075-T651 Aluminum.
RENSSELAER POLYTECHNIC INST TROY N Y DEPT OF MATERIALS ENGINEERING
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Corrosion fatigue crack propagation tests were performed on 7075 aluminum in dry argon, and solutions of NaCl and Na2SO4 under free corrosion conditions and under applied polarization. Bulk solution pH and oxygen level were also varied. Tests were also conducted in air after pre-exposure to an aggressive environment. Results indicate that both aqueous solutions appreciably increase fatigue crack growth rates. The Cl-ion generally produces the greatest increase in fatigue crack growth rate. Results indicate that adjusting bulk solution pH and decreasing the oxygen level can accelerate fatigue cracking. The magnitude of these effects is a function of the electrochemical conditions and the integrity of the oxide film at the crack tip.
- Properties of Metals and Alloys