The meaning and classification of stainless steel corrosion

Stainless Steel Corrosion

Corrosion is a process of deterioration or damage caused by a chemical reaction between a material and the environment. Metals are particularly prone to corrosion, which can lead to a change in the appearance and structure of the material, and can cause an item to deteriorate and become weak, resulting in various forms of failure and ultimately total degradation. As one of the most widely used metals, stainless steel offers great corrosion resistance due to its composition. However, even stainless steel can corrode in certain environments, and this must be taken into account when using the material. In this article, we take a look at different types of stainless steel corrosion and how each is caused.

Forms of Stainless Steel Corrosion

1. General Corrosion

General corrosion occurs when stainless steel is exposed to an environment that is highly corrosive, such as in an extremely wet or acidic environment, or where the chemical composition of the steel is not optimised. In this type of corrosion, the entire surface of the stainless steel is slowly corroded and can become very thin over time.

2. Localized Corrosion

Localized corrosion is a more specific type of corrosion that appears in a particular area of the stainless steel surface and does not tend to spread over the entire surface. This could occur when the surface of the stainless steel is contaminated with particles containing certain chemical compounds, or when certain forms of stress are applied.

3. Stress Corrosion Cracking

Stress corrosion cracking (SCC) is a form of corrosion that occurs when stainless steel is subjected to combined environmental and mechanical stresses. This type of corrosion is very serious, as it can lead to the failure of the material, resulting in dangerous results.

4. Intergranular Corrosion

Intergranular corrosion is a type of corrosion that occurs when a material is exposed to an environment containing certain levels of chlorides and sulphur compounds. As a result, the grains of the stainless steel alloy can become weakened and can lead to failure of the material.

5. Pitting Corrosion

Pitting corrosion is a type of corrosion that manifests as tiny holes or ‘pits’ on the surface of the stainless steel. It is caused by the presence of certain acidic compounds or low temperatures (less than 5°C) and the presence of chloride ions on the surface of the stainless steel.

6. Atmospheric Corrosion

Atmospheric corrosion is the type of corrosion that occurs in the atmosphere due to the presence of certain chemical compounds and oxide forming elements. This type of corrosion is particularly severe when the steel is exposed to moist air conditions.

Conclusion

Stainless steel corrosion is a process of deterioration of the material caused by a chemical reaction between the material and the environment. While stainless steel offers excellent corrosion resistance, this can be compromised if it is exposed to certain environments or stress conditions. In this article, we discussed the various forms of stainless steel corrosion and the factors that can cause them.

Corrosion of stainless steel, also known as stainless steel, refers to the phenomenon of oxidizing one or several types of metal on the surface of stainless steel due to the interaction between the metal and the environment, forming a specific oxide film.

Stainless steel corrosion is mainly divided into two categories, one is pitting corrosion and the other is crevice corrosion.

Pitting corrosion belongs to local corrosion, which is caused by uniform corrosion molecule diffusion in the materials, relatively weak oxide film on the metal surface and local factors. The corrosion cells on the surface of the material gradually grow, eventually leading to pits or crevices, which are mainly due to inadequate metal surface passivation or severe chloride ion erosion. The pitting corrosion of stainless steel is mainly caused by improper selection and combination of stainless steel or wrong environment.

The crevice corrosion of stainless steel is also a kind of local corrosion, which occurs in any gap or airtight parts, due to the corrosion formed in the gap, which is more serious than uniform corrosion. The crevice corrosion of stainless steel can be divided into two categories: one is due to the stopper effect, and the other is due to the accumulation of corrosion accelerated factors such as chloride ions in the gap. Crevice corrosion on stainless steel occurs mainly due to the accumulation of corrosive substances such as chloride ion in the gap.

In conclusion, the corrosion of stainless steel mainly includes pitting corrosion and crevice corrosion. Pitting corrosion is mainly caused by uneven passivation of metal surface, while crevice corrosion is caused by accumulation of corrosive substances such as chloride ions in the gap. To prevent corrosion of stainless steel, different preventive measures should be taken according to the different types of corrosion.