Corrosion is the degradation of a material in a corrosive environment, and is commonly divided into two groups; wet corrosion and high-temperature corrosion.

Wet corrosion

Wet corrosion occurs in the presence of a liquid containing ions, an electrolyte. Problems with wet corrosion attacks in stainless steels occur in mineral acids, process solutions, seawater and other chloride containing media. Examples of wet corrosion forms are:

There are various corrosion phenomena included in the above corrosion forms. For example, microbiologically influenced corrosion (MIC) and atmospheric corrosion in stainless steels are special cases of pitting and/or crevice corrosion.Selective corrosion is a special case of galvanic corrosion.

High-temperature corrosion

High-temperature corrosion refers to a chemical attack from gases, slags, molten salts or molten metals, typically in the temperature range above 400–500°C (750–930ºF) and up to about 1200°C (2190ºF). Examples of high-temperature corrosion are:

  • Carburization
  • Chlorination
  • Flue gas and deposit corrosion
  • Nitridation
  • Oxidation
  • Sulphidation