CORROSION

Corrosion is the deterioration of metals by the chemical action of some surrounding or contracting medium, which may be liquid, gas, or some combination of the two. To some degree, corrosion can influence all metals but its effect varies widely depending upon the combination of metal and corrosive agent.

Corrosion is used to describe action that is normally considered to be detrimental, but the principle is actually used for benefit in some cases. For example, acids and alkalis are used to corrode metal away in the manufacturing process of chemical milling. Also, aluminum alloys are frequently anodized to produce an oxide coating that resists further oxidation and, in addition, may serve as an improved surface for paint adhesion.

Corrosion attacks metals by direct chemical action by electrolysis (electrochemical action) or commonly, by a combination of the two.

There are several Corrosion Types that can occur. Some of the most important types of Corrosion are:

• Intergranular Corrosion
• Pitting Corrosion
• Sulphide Stress Corrosion Cracking
• Hydrogen Induced Cracking