Passivation of Stainless Steel & Stainless Steel Passivation Methods

The passivation of stainless steel is an integral process for components and parts made with stainless steel.

WHAT IS STAINLESS STEEL PASSIVATION?

Stainless steel passivation through electropolishing is a process that helps protect stainless steel surfaces from corrosion and rust. Stainless steel is considered “passivated” when it shows high resistance to corrosion in an environment where one would expect corrosion to take place. The process of passivating stainless steel helps to ensure the longevity of stainless steel products, making them more reliable and safer for use in a variety of industries. But what exactly is stainless steel passivation, and how does it work? Lets take a closer look.

Understanding Stainless Steel Passivation

The chromium in stainless steel forms a thin, oxygen-enriched, passive layer on the steel’s surface. This layer makes the metal resistant to corrosion. However, manufacturing processes such as cutting, machining, welding, and other production steps disrupt the passive layer and embed free iron and impurities into the surface layer of the metal. These impurities lead to corrosion. Stainless steel passivation works by removing any impurities or contaminants on the surface of the metal and restoring the chromium oxide layer that is normally present, thereby restoring the stainless steel’s inherent corrosion resistance.

Advantages of Stainless Steel Passivation through Electropolishing
There are multiple processes that can help to achieve passivation in stainless steel including nitric acid passivation and citric acid passivation. However, scientific studies have shown that stainless steel passivation through electropolishing is the most effective means of achieving passivation.

At NEE we agree; parts passivated through an abbreviated electropolishing cycle meet or exceed the corrosion resistance performance of parts passivated using a chemical method.

Passivation through electropolishing provides these key benefits:

The stainless steel passivation through electropolishing process is compliant with ASTM B 912-02 and ASTM A967-13, “Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts.”

Passivation through electropolishing removes all free iron from the surface of the work-piece, immediately eliminating free iron corrosion potential.

Electropolishing increases the chromium oxide layer to a greater degree than traditional passivation methods, thus enhancing the part’s corrosion resistance.

A mild electropolishing cycle removes a small amount of surface material, including additional free iron and deeply embedded impurities below the surface of the part.

Passivation through electropolishing increases the chromium oxide layer of stainless steel parts to a higher degree than chemical passivation methods, enhancing the part’s corrosion resistance.

All grades of stainless steel can undergo passivation through electropolishing, including: 301, 302, 303, 304, 316, 316L, 321, 17-4, 410, 416, 420, 431, 430, 440, 455, and F18.

Summary

In conclusion, the passivation of stainless steel is an important step in the manufacturing process for ensuring that your products remain safe and reliable over time by providing an extra layer of protection from corrosive elements present in the environment. It also provides improved aesthetics and makes cleaning parts easier too! With all these benefits of electropolishing in mind, it’s clear why many product engineers utilize electropolishing to achieve stainless steel passivation. To achieve passivation in stainless steel for your products, contact the experts at New England Electropolishing today. We offer a free sample part electropolished and shipped back to you at no cost.

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