How Electropolishing Improves Corrosion Resistance

Electropolishing is widely specified to enhance corrosion resistance on a wide variety of metal alloys. Although most commonly used on stainless steels, electropolishing offers corrosion resistance on other alloys as well. Due to the versatility and superior effectiveness, electropolishing is fast becoming a replacement process for passivation.
Corrosion resistance and electropolishing

Limitations of Passivation

Passivation is a chemical process that has been used for years to help restore contaminated stainless steel to original corrosion specifications. Passivation is routinely specified by engineers because of the many sources of contamination. The intent of passivation is to remove free iron or other foreign matter from the surface of the metal and to create 
a chromium rich surface that is resistant to corrosion. However, passivation is generally not effective in removing embedded free iron and contaminants and will not remove heat tint or oxide scale on stainless steel.

Engineers looking to pass stringent salt spray and humidity tests have turned to electropolishing for a more aggressive replacement for passivation. The electropolishing process dissolves the outer skin of metal, removing deeply embedded contamination. Heavily contaminated surfaces such as machined parts, welded or brazed assemblies or other components that typically respond poorly to passivation alone, are good candidates for electropolishing. Unlike passivation, all stainless alloys including the 400 series and precipitating grades can be processed without distortion, flash attack or hydrogen embrittlement.

Just as electropolishing is used to enhance corrosion resistance on stainless steel, it offers corrosion resistance on other alloys as well. Many companies use the process to delay or retard the corrosion properties of copper, brass, aluminum, and carbon steels. On these and other alloys, the removal of surface skin and impurities enhances the corrosion resistant properties of the component.

The parts pictured on the right are made from type 303 stainless steel. After a series of machining operations, the parts needed to be decontaminated to remove embedded steel and other impurities.

Under 40X magnification using the scanning electron microscope, you can see the passivated part is actually rougher, due to the chemical attack of the 303 stainless steel by normal passivation. In contrast, the electropolished part is smooth and clean. By carefully monitoring the amount and rate of metal removal, electropolishing dissolves the surface skin and its impurities, including impinged steel flecks and other contaminants.

Whitepaper: Advantages of Electropolishing for Deburring Metal Parts

Electropolishing, with its ability to remove a microscopically precise layer of surface material with consistent results, is the finishing process of choice for such parts, for many reasons. Learn why electropolishing is more effective than other methods for removing burrs.

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Whitepaper: Electropolishing to Improve Corrosion Protection

Discover why one of the most common applications for electropolishing is to enhance corrosion resistance on a wide variety of metal alloys, specifically stainless steel. These two case studies show why electropolishing has become a replacement process for passivation.

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Contact us to learn more about electropolishing and corrosion resistance

Medical Device Manufacturing

Our tightly controlled quality process and ISO 9001 and ISO 13485 certifications make us the preferred partner for many medical device manufacturers across the globe. From implantable devices to surgical instruments, electropolishing is a single-process treatment that results in biocompatible, safe and ultra clean parts.

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Aerospace

We offer aerospace vendors and original equipment manufacturers our signature metal finishing services to increase fatigue-resistance for their metal parts, rendering them capable of withstanding the stress and corrosion that comes with long-term use. Surface abnormalities lead to part failure, but with electropolishing, parts become more reliable and long lasting.

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Pharmaceutical

Our strict adherence to industry standards ensures that pharmaceutical components are electropolished in accordance with ASTM B912 and ASME BPE specifications. These products are clean and smooth, corrosion resistant and contaminant free.

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Automotive

Corrosion resistance and microfinish improvement are essential for critical automotive parts, making electropolishing an increasingly beneficial option for automakers. Electropolishing both interior and exterior auto parts ensures they will resist premature failure and function at an optimal level.

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Consumer Appliance

Notable examples of appliance parts we electropolish are 400-series stainless steel alloys used in many consumer appliances. Our metal finishing services help increase corrosion resistance for these parts, and by removing the outermost layer of metal withelectropolishing the durability and longevityof these appliance components is increased.

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Food & Beverage

We have a long history of working with the food and beverage industry. Electropolishing materials for this industry eliminates the buildup of bacterial biofilms, as well as keeping the equipment free of contaminants like Salmonella. When it comes to food and beverage processing equipment, safety and cleanliness are of the upmost importance and electropolishing delivers the level of sanitation required by a number of regulatory agencies.

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Hydraulics & Pneumatics

From robotics to heavy mobile equipment, the uses of electropolishing in the hydraulics and pneumatics industry are many. By helping prevent premature part failure, electropolishing reduces the amount of downtime and increases the life cycle of these components. Proper surface finish and cleanliness is key in this industry, and electropolishing attains the finishour customers require.

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Electronics

Improving conductivity and performance is just one benefit electropolishing offers for electronics parts. The surface finish is improved by as much as 50 percent, removing imperfections from the material without removing a lot of material removal from the component.

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