Dezincification

There are essentially two forms of dezincification: uniform and localized. Uniform dezincification occurs when zinc is leached from a broad area of the brass surface, whereas, the localized form, also known as plug-type dezincification, penetrates deeply into the brass. In the localized form, the metal in the surrounding area is not significantly corroded by dezincification.

The widely accepted mechanism of dezincification involves the dissolution of brass where the zinc remains suspended in the corrosive solution while the copper is plated back on to the brass. Although dezincification can occur in the absence of oxygen, its presence accelerates the corrosion rate. Copper-zinc alloys with greater than 15% zinc are susceptible to dezincification. Figure 14 shows a photograph of corrosion by dezincification.