Corrosion of the Welded Aluminium Alloy in 0.5 M NaCl Solution. Part 1: Specificity of Development.

Andrey Gnedenkov,Dmitry Mashtalyar,Vladimir Egorkin,Sergey Gnedenkov,Sergey Sinebryukhov,Igor Vyaliy

doi:10.3390/ma11102053

Abstract

This work consists of two parts. In the first part, the kinetics and mechanism of corrosion on the surface of the welded joint area of the aircraft 1579 aluminium alloy have been studied using SVET (scanning vibrating electrode technique) and SIET (scanning ion-selective electrode technique) in 0.5 M NaCl. The results have revealed the corrosion process development within the weld interface due to the presence of microdefects in the morphological structure. Features of the 1579 Al alloy corrosion have also been investigated through immersion experiments, quantitative analysis of dissolved alloying elements by means of atomic absorption spectroscopy, and corrosion products characterization using XRD (X-ray diffraction) analysis. The presence of Mg as an alloying element in the 1579 Al alloy sufficiently increases the bulk pH values as a result of the intensive dissolution of Mg. These factors accelerate the corrosion activity of the studied material in the 0.5 M NaCl solution. Corrosion evolution analysis of the 1579 Al alloy sample showed the importance of the coating formation to protect this alloy against corrosion and to increase the stability of this system in the corrosive media.

Highlights

Aluminium alloys are used in various fields of industry, in automobile, construction, and engineering structures, and, especially, in the aerospace industry
The analysis of the results indicates the uniform distribution of elements on the surface of the aluminium plates and welded joint area of the sample
These results indicate the possibility of a uniform propagation of the electrochemical processes on the surface of the indicate the possibility of a uniform propagation of the electrochemical processes on the surface of material, which will be studied by scanning vibrating electrode technique (SVET) and selective electrode technique (SIET) measurements

Summary

Introduction

Aluminium alloys are used in various fields of industry, in automobile, construction, and engineering structures, and, especially, in the aerospace industry. Aluminium alloys are effective materials for the reduction of construction or vehicle weight, which expands their fields of application. Pure aluminium has a high resistance to corrosion as a result of a protective film formed on its surface during exposure to air or immersion in aqueous solutions. Due to the presence of anodic and cathodic intermetallic particles in the composition of Al alloys, these materials are not sufficiently resistant to the localized corrosion process to be used for external applications without protection when exposed to aggressive media, such as marine environments [1,2,3,4,5]. In [1] Moreto et al used electrochemical impedance spectroscopy (EIS), scanning Kelvin probe (SKP), and the scanning vibrating electrode technique (SVET) in order to assess the global and localized electrochemical behaviour of four aluminium alloys (AA2524-T3, AA2198-T851, AA7050-T7451, and AA7081-T73511) used in aircraft fabrication

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Results

Conclusion