Stainless steel is a metal alloy known for its low oxidation rate, making it a material unlikely to corrode. This property stems from the approximately 11% chromium content used in its manufacture. The most effective way to protect a metal structure from corrosion is to prevent its surface from contact with the environment through the stainless steel's passive layer.
If you want to prevent damage to a steel object, especially in areas with high corrosion potential, it's important to understand how this layer of steel works. This will help you better plan your projects and create higher-quality steel components.
Follow along and learn more about the passive layer of stainless steel, how it forms, and its importance.
The passive layer of stainless steel is a barrier that forms when chromium comes into contact with oxygen. This reaction makes the material as a whole more resistant to oxidation.
Corrosion is very common in metallic materials and occurs from the interaction between steel and the environment. Oxygen and water are the main culprits of this oxidation.
Steel deterioration causes a decrease in strength, leading to failures and breakages, in addition to having a negative aesthetic effect. Depending on the elements used in the metal alloy, we can determine whether the steel reacts more or less strongly to the environment.
Chromium, together with other elements, when in contact with the external environment, forms a layer known as a passive layer or passive film on the surface of the stainless steelThe passive layer of stainless steel is very thin and forms across the entire surface, with strong adhesion to the steel, preventing corrosion and increasing the strength of the part.
Stainless steel is a highly versatile metal alloy widely used in household appliances, construction, and other sectors. Stainless steel's passive layer allows it to be used in a wide variety of environments without losing its properties.
In a brief comparison with other types of steel, it is possible to list several advantages of stainless steel, such as its high corrosion resistance (the most well-known) and ease of welding. In addition to its mechanical properties, stainless steel has a hygienic appearance and is easy to clean. Therefore, it is widely used in domestic environments due to the beauty and modernity of its finish.
Stainless steel is also an inert material, meaning it doesn't come into contact with other substances, reducing the risk of contamination. For this reason, it's widely used in places where this property is required. The many qualities and uses of stainless steel make it an indispensable material in the inventory of construction material stores and commercial establishments specializing in iron and steel.
An interesting characteristic of the passive layer of stainless steel is that, in many cases, it can form naturally through contact with the environment. However, there are also situations where its formation is induced by chemicals.
When chromium comes into contact with an environment with a high concentration of oxygen, these elements react with each other, creating chromium oxides and hydroxides in a process called stainless steel passivation. After this reaction, the stainless steel gains a protective layer of oxidized chromium that does not react with the oxygen in the environment.
Stainless steel's passive layer is ideal for preventing corrosion, but it requires some care. Below are the main factors you should be aware of.
Despite preventing oxidation, the passive layer can still be damaged by other corrosive substances, such as salinity in the air, which is common in coastal regions. The same goes for strong chemicals, which are not suitable for cleaning stainless steel.
The passive layer is very thin and adheres to stainless steel, and any abrasive material can remove parts of this layer, creating spots where the steel can corrode again. Therefore, it's important to be extra careful when handling this material.
Even with all due care, stainless steel's passive layer tends to deteriorate over time. To prevent its loss, it's important to properly maintain stainless steel, which involves cleaning—and in some cases, replacing—this layer using chemical processes.
In locations near the sea or in environments with properties that can damage stainless steel, it's important to consider some conservation measures. Below, we list the main precautions.
As mentioned, cleaning stainless steel is essential to preserving the passive layer. This prevents the buildup of dirt and particles that could cause grooves or other damage to the layer. It's worth remembering that only products specifically designed for cleaning stainless steel should be used.
You can also reduce the risk of corrosion by reducing the stainless steel's exposure to harmful external factors. Some examples include keeping windows closed throughout the day to avoid salty air and covering objects when not in use. These measures extend the material's lifespan and reduce maintenance costs.
Finally, it's necessary to reapply the stainless steel passive layer periodically to ensure adequate protection. This process involves removing the existing layer, reapplying the chrome, and then promoting the necessary chemical reactions again.
Now you know more about stainless steel's passive layer. It's a process that can be induced or occur spontaneously, giving the material superior oxidation resistance. This property is important in any project involving steel.
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