Galvanic Corrosion

Galvanic corrosion is a little more difficult to keep track of in the industrial world. You'll notice below that simply adding a screw of the wrong material can have severe consequences. Galvanic corrosion occurs when two metals having different composition are electrically coupled in the presence of an electrolyte. The more reactive metal will experience severe corrosion while the more noble metal will be quite well protected. Perhaps the most infamous examples of this type of corrosion are combinations such as steel and brass or copper and steel. Typically the steel will corrode the area near the brass or copper, even in a water environment and especially in a seawater environment. Probably the most common way of avoiding galvanic corrosion is to electrically attach a third, anodic metal to the other two. This is referred to as cathodic protection.

Figure 2: Galvanic Corrosion