The Corrosion Resistance of Hard Anodised EN AW 7075 T6 Alloy

The Corrosion Resistance of Hard Anodised EN AW 7075 T6 Alloy

Paper in proceedings (conference paper)

In this paper, commercially cold-rolled and artificial aged EN AW 7075 T6 alloy has been used. To ensure increased corrosion resistance, surface hardness, scratching resistance, and aesthetic features, this aluminium alloy was subsequently hard anodised and hot-water sealed (AC-A). The hard anodizing and sealing process increased surface hardness up to 304 13 HV 1 from an initial surface hardness of 194 3 HV 1. Also, the microhardness of the anodised layer and bulk material has been documented. Scanning electron microscopy (SEM) was used for microstructure and trapped precipitates investigation in the 42.9 1.4 thick formed anodised layer investigation. The T6 treated (AC) and hard anodised together with sealed (AC-A) EN AW 7075 alloy corrosion properties were evaluated using the anodic potentiodynamic polarisation tests (PPT) in a neutral 2.5% NaCl deaerated solution. The corrosion rate CR (mm/y) decreased approx. 39-times for the hard anodised and sealed EN AW 7075 alloy (AC-A), associated with the shift of the E corr (mV) to more positive values, degreased Icorr (µA) and increased Rp (Ohm) values compared to the artificial aged (AC) alloy. Additionally, the pitting was evaluated using laser confocal microscopy, and the pitting coefficient was also calculated.

In this paper, commercially cold-rolled and artificial aged EN AW 7075 T6 alloy has been used. To ensure increased corrosion resistance, surface hardness, scratching resistance, and aesthetic features, this aluminium alloy was subsequently hard anodised and hot-water sealed (AC-A). The hard anodizing and sealing process increased surface hardness up to 304 13 HV 1 from an initial surface hardness of 194 3 HV 1. Also, the microhardness of the anodised layer and bulk material has been documented. Scanning electron microscopy (SEM) was used for microstructure and trapped precipitates investigation in the 42.9 1.4 thick formed anodised layer investigation. The T6 treated (AC) and hard anodised together with sealed (AC-A) EN AW 7075 alloy corrosion properties were evaluated using the anodic potentiodynamic polarisation tests (PPT) in a neutral 2.5% NaCl deaerated solution. The corrosion rate CR (mm/y) decreased approx. 39-times for the hard anodised and sealed EN AW 7075 alloy (AC-A), associated with the shift of the E corr (mV) to more positive values, degreased Icorr (µA) and increased Rp (Ohm) values compared to the artificial aged (AC) alloy. Additionally, the pitting was evaluated using laser confocal microscopy, and the pitting coefficient was also calculated.

corrosion resistance; 7075-T6; aluminum corrosion

corrosion resistance; 7075-T6; aluminum corrosion

KUSMIČ, D.; KLAKURKOVÁ, L.; JULIŠ, M.; GEJDOŠ, P.; VILIŠ, J.; ČECH, O.

2022

22.08.2021

Electrochemical Society

9781607685395

ECS Transactions

105

1938-6737

ECS Transaction

105

1

United States of America

329

337

9

https://iopscience.iop.org/article/10.1149/10501.0329ecst

http://hdl.handle.net/11012/203542

The-Corrosion-Resistance-of-Hard-Anodised-en-AW-7075-T6-AlloyECS-Transactions
10501.0329ecst_accepted