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Stainless Steel Passivation: What It Is & How It’s Done.
By ridgexmetals.com

Stainless Steel Passivation: What It Is & How It’s Done.

Stainless Steel Passivation: What It Is & How It’s Done

Passivation is a process by which stainless steel surfaces are made corrosion resistant. The corrosion resistance of stainless steel increases with passivation, making it the go-to process for many industries who require corrosion resistance in their products.

What Is Passivation?

Passivation is an electrochemical process in which an oxide layer is formed on the surface of the stainless steel by reacting with the air in the environment. This oxide layer is also known as a passive layer and it acts as a protective barrier between the underlying steel surface and any potential corrosive elements.

How Is Passivation Done?

There are several common techniques and processes used to passivate stainless steel, including acid passivation, alkaline passivation, and electropolishing.

Acid Passivation

Acid passivation involves immersing the stainless steel in an acid bath, usually nitric acid or citric acid, to remove any impurities, such as iron particles, from the surface and form the protective oxide layer. This method is typically used on parts with complex shapes, since they can be more easily submerged in the acid solution.

Alkaline Passivation

Alkaline passivation, also known as pickling, is a common method for removing iron particles from the surface of stainless steel components. Alkaline solutions, such as sodium hydroxide, are applied to the surface of the part and left for a certain amount of time. The time depends on the nature of the part and desired results.


Electropolishing is a process that removes impurities from the surface of stainless steel through an electrochemical process. It is considered a superior passivation technique as it not only removes impurities but also improves the surface finish and improves the corrosion resistance.

Benefits of Passivation

Passivation offers numerous benefits, including:

  • Corrosion Resistance: Passivation leads to an increase in corrosion resistance, reducing the risk of rust development and protecting the underlying stainless steel surface.
  • Cost Savings: Passivation offers cost savings as it can significantly reduce the need for repairs and maintenance over the long term.
  • Thinner Coatings: Passivation reduces the need for thicker coating applications, helping to reduce overall cost and improve product appearance.

Passivation is an effective and cost-efficient way to improve the corrosion resistance and overall performance of stainless steel products. It is widely used in many industries and is an important part of the solution to rust and wear protection. Stainless steel passivation is a process that improves the corrosion resistance of stainless steel parts and components. The process involves cleaning the surface of the part with certain chemicals, then treating it with an acid solution. The resulting corrosion resistance can extend the life of the part significantly.

Passivation is considered to be the last stage in the fabrication process of all stainless steel components. It works by creating a thin, invisible film on the surface of the steel that prevents corrosion. The passivation process helps to remove free iron and other foreign particles present on the surface, protecting the steel against corrosion.

The specific procedure depends on the grade of stainless steel and the surface finish. The process may involve using either a citric acid bath or nitric acid bath. The acid bath helps to remove impurities from the steel and increase its corrosion resistance. After the acid bath, a sealant may be applied, such as wax or oil, to reduce the risk of corrosion.

It is important to note that the passivation process does not add any protective properties to the steel; instead, it helps to restore the original protective properties. Additionally, any damage to the layer of passivation, such as abrasive brushing or welding, must be repeated.

The benefits of stainless steel passivation include increased resistance to corrosion, improved durability, and improved aesthetic appeal. When done correctly, stainless steel passivation can significantly extend the life of the part and components, saving costs in the long run.

For these reasons, stainless steel passivation is an essential step in the manufacture of many stainless steel parts and components. The process is simple but must be performed correctly in order to provide maximum protection against corrosion. In addition, regular maintenance is necessary in order to maintain the beneficial properties of the passivation layer.

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  • 11/01/2023

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