Corrosion of duralumin was studied in sandy soil conditions with different moisture and ion concentrations. The influence of these factors on initial (the first hours) corrosion stages was visualized by a chemographic method in which a film works as an indicator of the volatile products released during the electrode process, which may transform silver to the metallic state. Atomic hydrogen acts as such a product during metal corrosion. As a result, the pattern of optical density in a chemogram maps the corrosion activity of a specimen surface. The soil condition was checked by using its conductance. Two mechanisms of conductance were differentiated and analysed in terms of the percolation theory for low-moisture soil (<1% mass moisture) and high-moisture soil. It was found that the ion concentration in solution has no practical influence on conductance at low moisture. Traced reactions of duralumin corrosion show that this process is different in low-and high-moisture soils. Pitting corrosion was visualized at the very beginning, with pits being located immediately and precisely on the surface of model specimens. Patterns of duralumin corrosion were traced in cases when cathode protection was applied and when a duralumin specimen worked as a sacrificial anode. The results of this research can be used to develop electrochemical corrosion protection systems for underground metal constructions.

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