Abstract
Effect due to ageing time and stress on the corrosion behavior of Aluminum-Coper alloy AA 2024-T6 is studied. The alloy specimens were aged for 6 hrs, 9 hrs and 12 hrs ageing time and then subjected to corrosion testing in saturated Sodium Chloride (NaCl) solution. Constant Stress of 0.25Ꮄy (yield strength) using four point bend apparatus is applied on a 9 hrs aged sample and this setup is immersed in the saturated NaCl solution to study the effect of stress. Polarization curves of the aged specimens having same exposed area showed that the specimens corroded majorly by pitting mechanism which is supported from SEM micrographs. The sample aged for 9 hrs had the least corrosion resistance but the samples aged for 6 hrs and 12 hrs had 11% and 28% increase in the corrosion resistance. However, the sample aged for 9 hrs had the highest hardness, making it a good candidate out of the three for structural applications where corrosion resistance is also important. Polarization curves of non-stressed and stressed specimens having same exposed area showed a 70% increase in the corrosion rate of the latter, calculated from the marked area of the polarization curves along with a decrease in the passive region. The former corroded by pitting mechanism while the latter corroded by filmdissolution mechanism which is inferred from SEM micrographs.

Zaigham Saeed Toor, Ishaq Ahmed, Sajid Ullah, Akbar Niaz Butt, Syed Wilayat Hussain. (2018) Influence of Ageing time and Stress on Corrosion behavior of AA2024-T6 in saturated NaCl Solution, Journal of Space Technology , Volume 8, Issue 1.
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