Corrosion is a natural process that occurs when metals react with their environment, leading to the deterioration of the metal surface, loss of mechanical properties, and ultimately, structural failure. This process can be accelerated by various factors, such as high temperature, humidity, presence of contaminants, and exposure to corrosive agents. Corrosion can occur in a variety of forms, and its effects can range from mild discoloration to catastrophic failure, depending on the type and severity of the corrosion.
In this article, we provide a comprehensive classification of 12 types of corrosion with pictures and detailed explanations of each type, to help readers identify and address potential corrosion issues in their assets. We also discuss the factors that contribute to corrosion and share best practices for corrosion prevention and mitigation.
Types of Corrosion
The following different types of corrosion
- Atmospheric Corrosion
- Erosion Corrosion
- Selective Corrosion
- Uniform Corrosion
- Pitting Corrosion
- Fretting Corrosion
- Stress Corrosion
- Inter-granular Corrosion
- Corrosion Fatigue
- Galvanic corrosion
- Waterline Corrosion
Here, we discussed above mention types of corrosion with pictures briefly,
1. Uniform Corrosion
Its name suggests uniform corrosion is formed in a uniform layer on the surface of metals and that is extended all over the surface of the metal and also this type of corrosion is mostly seen in metal materials such as zinc, lead, aluminum, etc, and it cannot be protected by surface coating treatment.
Also, uniform coating is also known as a general type of corrosion and these uniform corrosions have a relatively low impact on the performance of the material.
The uniform corrosion is prevented by some methods,
- Modify the environment
- Use anodizing
- Use corrosion inhibitors
- Use thicker material for allowance of corrosion
2. Inter-granular Corrosion
Intergranular corrosion occurs along the grain boundaries and grains are not affected in that case. It is caused when there is a noticeable difference in reactivity against impurities grains and grain boundaries also this difference occurs due to heat treatment, stainless steel, copper, and defective welding.
3. Stress Corrosion
This stress corrosion occurs by the combination of mechanical stress and corrosive environment stress on the surface of the material, and initially, small cracks are developed lastly this crack leads to the failure of the whole structure, and the stress corrosion is unpredictable in nature. Also, you can call an “SCC” is abbreviated form of stress corrosion cracking.
In that case, when stainless steel is stressed in chloride environments at that time stress types of corrosions are occurred, and another side when brass materials are stressed in the ammonia at that time stress corrosions occur, and the caustic embattlement of mild steel and seasonal crack is the best example of stress cracking.
4. Pitting Corrosion
As the name suggests pitting corrosion forms rust pits or holes on the metal surface, and it is a localized form of corrosion, in a small area shape of a rust pit may not be similar but in most cases, corrosion is hemispherical in shape and also it is the very unpredictable and dangerous type of corrosion so that difficult to detect them.
Commonly this pitting corrosion occurs in aluminum, nickel alloys, steel and etc.
5. Atmospheric Corrosion
Atmospheric corrosion is a wet type of corrosion that is caused by the action of the electrolyte, in the rainy season atmosphere is damp at that time electrolytes trigger corrosion of the exposed metal surface.
6. Erosion Corrosion
Erosion Corrosion is caused by mechanical abrasion due to the movement between corrosive fluids and the metal surface, in that case, the metal surface gets damaged or deteriorated slowly by the abrasion of fast-moving fluids. Also, erosion-corrosion has mostly seen in metal tubes carrying moving fluids in them.
7. Selective Corrosion
Selective types of corrosion occur in alloys where one of the metal components is de-alloyed by the corrosive environment, this type of corrosion can be seen in brass alloy pipes where zinc is commonly used as another component, and here zinc metal is de-alloy.
8. Fretting Corrosion
Fretting is a combined action of fretting as well as corrosion at points where two metal plates or surfaces make contact by means of gnawing action or rubbing action, fretting corrosion is sometimes known as chafing corrosion.
This fretting corrosion can be seen in rivet joints, clamped surfaces, bolted connections, and rivet joints.
Fretting types of corrosion can be prevented by the following points:
- Use contact lubricant.
- Using seals for absorbing vibration.
- Increase the hardness of both material and one material.
- Also, reduce the movement between two materials.
- Using those materials which are susceptible to fretting corrosion.
9. Corrosion Fatigue
Corrosion fatigue by defined as fatigue in a corrosive environment, and also an aggressive environment can be harmful to the fatigue life of a structure, and protection against corrosion is necessary.
The surface of a material can be loaded dynamically at that time corrosion fatigue can be a serious problem, and it can be prevented by improving the fatigue resistance material.
10. Corrosion Fatigue
This Galvanic corrosion occurs when different metals are exposed to a corrosive atmosphere, the metal which has a higher electrode potential value will form an anode and undergoes this type of corrosion.
11. Water line Corrosion
The oxygen concentration dissolved in water is greater at the surface than deep, this lead to the formation of a concentration cell, an anode has a lower portion, and the cathode is at the water level.
Due to poor water conductivity, the ions below the water level and available for reaction and the metal surface corrodes below the water level.
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