Direct Current Corrosion (DC Corrosion)

Definition - What does Direct Current Corrosion (DC Corrosion) mean?

Direct current corrosion, as its name suggests, is a type of corrosion caused by DC. This may originate from sources of current like DC welding, rail transit as well as cathodic protection systems.

It is considered to be one of the most serious forms of stray current corrosion, as DC flow is not stable in terms of current paths and magnitude.

Corrosionpedia explains Direct Current Corrosion (DC Corrosion)

Electric currents can cause corrosion under particular situations. The attack can be seen on steel and iron along with other types of technical metals. Direct currents that pass through the surface of steel are entirely resistive current. The current can promote surface oxidation, which can be exhibited by metal loss based on Faraday's law.

The law states that steel and iron metal loss rate is 9.1 g iron/mA per year. The exiting current leads to a heightened potential on the surface of the metal that has anodic or positive direction. The amount of the rise in potential is the function of the DC density.

However, current that enters the surface does not result in corrosion, but rather provides cathodic protection or corrosion protection on the surface. This protection is brought about by the recution of potential in the negative or cathodic direction.

Thus, concerned industries should practice accurate assessment and recording of direct stray current activities, such as in pipelines to gauge and control the effects of stray currents.

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