4. Forms of Corrosion

4.1 Introduction

The impact of corrosion ranges from being merely a cosmetic damage to a severe break-down of critical components leading to a catastrophic loss in terms of lives, equipment and valuable time. Proper material selection is a first step towards controlling corrosion. In order to be able to select suitable materials, it is important for an engineer to understand the nature of corrosion, types of corrosion and methods of prevention of different types of corrosion.

Depending on the materials and environmental conditions, corrosion can take various forms such as


Uniform or General Corrosion


Galvanic Corrosion


Pitting Corrosion


Intergranular Corrosion


Stress Corrosion Cracking

6. Hydrogen Blistering

Hydrogen Induced Cracking

8. Sulfide stress corrosion cracking
9. Caustic Cracking
10. Crevice Corrosion

In the following sections, the mechanism, environment and methods of prevention are discussed. Photographs of actual failures under each category are also presented.