THE EFFECT OF THREE TYPES OF HEAT TREATMENT ON THE HARDNESS AND
CORROSION RESISTANCE OF Al 2014 ALLOY
Abstract
Al 2014 is a high-strength aluminum alloy widely used in
the aerospace and automotive industries for its mechanical robustness.
This study investigates the impact of three heat treatment
processes—Retrogression and Re-aging (RRA), T6 standard aging, and a
modified RRA with high-temperature pre-aging—on the hardness and
corrosion resistance of Al 2014. Potentiodynamic electrochemical
polarization studies in a 3.5 wt% sodium chloride solution assessed
corrosion resistance, revealing that heat treatment, which induces
precipitation hardening, shifted the corrosion potential (E) toward the
noble direction. The formation of Al2Cu precipitates is linked to
enhanced corrosion resistance. Furthermore, T6-treated samples exhibited
a higher corrosion current density compared to untreated Al 2014 alloy
samples, suggesting superior corrosion resistance. Scanning electron
microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS)
analysis of corroded surfaces showed evidence of general and pitting
corrosion, with distinct patterns among the three heat treatment
processes. Comparative analysis revealed that the T6 standard aging
process offered the best hardness and corrosion resistance, likely due
to stable precipitate formation during aging. RRA also delivered good
performance, suggesting it is a viable alternative where a balance
between hardness and toughness is needed. The modified RRA with
high-temperature pre-aging yielded lower performance, likely due to
overaging, reducing hardness and corrosion resistance. These findings
underscore the importance of heat treatment in enhancing the corrosion
resistance of Al 2014 alloy, suggesting that specific processes can
improve the alloy’s durability in corrosive environments, leading to
extended lifespan and reduced maintenance costs.
