Sequential Trends in Corrosion Behaviour of Surface-Ground Aluminium 7075 Thin Plates in 3.5 wt% NaCl Solution he Potentiodynamic Polarization Method

Abstract

The primary aim of this study is to assess the corrosion behavior of Aluminum 7075 plates in a 3.5 wt% NaCl solution after undergoing surface grinding. Aluminum 7075 plates are ground according to a  factorial design schedule, and their corrosion behavior is evaluated using a CorrTest Electrochemical Workstation. The trends of the Tafel plots for the 54 samples are analyzed in groups of five runs except the last group which consists of four runs. It is found that the anodic Tafel slope (23.77 mV) is lower at a low table speed (2.0 spm) and moderate grinding depth (0.5 mm). High feed (5.0 mm) and grinding depth (1.0 mm) eventuate to a higher cathodic Tafel slope (86211400.0 mV) due to increased strain hardening. With low feed (1.0 mm), the corrosion potential is lower (-0.796 V), whereas a moderate feed (2.0 mm) results in a higher corrosion potential (-0.640 V). At a low table speed (2.0 spm), the corrosion current density (0.000032 A/ ) is low, and conversely, when the table speed increases, this density rises. A high feed rate (5.0 mm) corresponds with a high corrosion current density (0.000406 A/ ) and vice-versa, as the grinding tool processes a larger surface area, potentially increasing surface roughness. It is found that with a low grinding depth (0.2 mm), the corrosion current density is elevated (0.000406 A/ ), and the opposite is true when the depth increases. When the table speed is reduced (0.2 mm), the polarization resistance is high (812.5 Ω. ), and this resistance decreases as the speed increases. Moreover, a high feed (5.0 mm) results in a lower polarization resistance (64.04 Ω. ) and vice versa. Additionally, with a low grinding depth (0.2 mm), the polarization resistance is reduced (64.04 Ω. ), while an increase in depth raises the resistance.