Question

What are the two types of corrosion?

Answer 1

Corrosion:
Corrosion is a natural process in which a metal undergoes chemical reactions with its environment, gradually destroying the metal by converting it into its stable oxide.

Two types of corrosion are given below.

1. Pitting Corrosion: This is an extremely localised form of corrosion that leads to the formation of small holes in the metal. It starts with the oxidation of metal at a localised point resulting in the formation of a ‘Pit’. Once formed, this pit continues to grow vertically, penetrating the metal. If left unchecked, it will lead to structural failure. This form of corrosion is very unpredictable and dangerous.
2. Stress Corrosion Cracking: Stress corrosion cracking refers to the growth of cracks within the metal at elevated temperatures when subjected to a corrosive environment and tensile stress. An example of this type of corrosion is the cracking of stainless steel in presence of alkali which occurs in stainless steel boilers.