Corrosion behavior of alloy AA6063-T4 in HCl and NaOH solutions

Abstract

AA6XXX aluminum alloys are widely used in the automotive and aeronautic industries and for food packaging thanks to their lightness, specific strength, and corrosion resistance. The mechanical properties of AA6XXX alloy increase through an age hardening process thanks to the formation of Mg2Si particulates. These particulates enhance mechanical strength and likewise change corrosion resistance. In this study, the corrosion behavior of AA6063-T4 alloy in acidic and alkaline media was investigated and the results were compared with AA6063-T651 alloy. Acidic media was prepared in a 0.1M HCl solution; alkaline media was prepared in a 0.1M NaOH solution. Corrosion tests were performed for 360 hours in both solutions. Corrosion properties were determined by measuring weight loss and surface roughness values of the samples and pH values of the solutions. In both environments, artificially aged samples were found to have higher corrosion rates. There was a direct relationship between corrosion loss and surface roughness values.

Corrosion behavior of under‐, peak‐, and over‐aged 6063 alloy: A comparative study

“…The corrosion rate of OA alloy is the highest amongst three states of ageing at any particular t i . It is known that higher pH values have a lower corrosion rate and vice versa . This observation is consistent with the results in Figure b.…”

“…This observation is consistent with the results in Figure b. The reduction in corrosion rate is attributed to the accumulation of corrosion products at the interface of the specimen and the corrosion medium . The FE‐SEM images in Figures a1, a2, and a3 show a distinct variation in the corrosion morphologies of an OA alloy for immersion times of 6 h, 72 h, and 336 h respectively.…”

“…It is known that higher pH values have a lower corrosion rate and vice versa. [8,49] This observation is consistent with the results in Figure 3b. The reduction in corrosion rate is attributed to the accumulation of corrosion products at the interface of the specimen and the corrosion medium.…”

“…[6] Wrought aluminum alloys of 6xxx series grade are frequently being used in automotive, construction, and shipbuilding industries because of their high specific strength, good fabricability, weldabilty, and their ability to naturally form an oxide layer on the surface, which can resist the atmospheric corrosion. [7][8][9] An ideal route to improve the mechanical properties of Al-Mg-Si alloys is to expose them to ageing treatments for the precipitation of intermetallics from the solute atoms within the matrix of the alloy. [7] The influence of ageing treatment on the mechanical properties, [10][11][12][13] fatigue [14][15][16][17] and tribological behavior [18,19] were extensively studied for this kind of alloys in the past.…”

“…[24][25][26] Thus, the microstructural state of an agehardenable alloy is also important in defining its corrosion characteristics. Several earlier researchers [5,8,9,[27][28][29] have focused on a number of issues regarding the corrosion of heat treatable alloys. However, a comparative study on the corrosion behavior of different microstructural states is limited in the existing literature.…”