Citric passivation is a fast, cost-effective and environmentally friendly method of increasing corrosion resistance for stainless steel parts that is increasingly in demand in aerospace and manufacturers.
Stainless steel is naturally resistant to corrosion but machining introduces free iron that can create initiation sites for corrosion that will continue to spread unless it is removed. Citric passivation removes free iron contamination.
Stainless steel parts are immersed into an oxidizing bath consisting of naturally occurring acids found in oranges and other citrus fruits, which is biodegradable and more environmentally friendly than nitric passivation. The citric acid bath creates a thin yet dense, protective oxide layer that makes stainless steel parts corrosion-resistant and clean once again.
Our citric passivation services conform to ASTM A967, ASTM A380, AMS 2700, and QQ-P-35C.
As explained in Euro Inox’s publication Pickling and Passivationg Stainless Steel, “Steel delivered from manufacturing mills and reputable stockholders will be fully passive. The treatment may be needed however on intricately shaped machine parts. In these special cases, the supply of oxygen to all the newly formed surfaces may be restricted, resulting in the natural passivation process taking longer to complete, than on the open, exposed surfaces. There is a danger that if parts like these are put straight into service in an environment normally considered suitable for the particular steel grade used, they might not be fully passive and suffer unpredictable corrosion. Passivation treatments done under these circumstances eliminate these unnecessary corrosion risks.”
Only electropolishing removes burrs, micro cracks and other contaminants by dissolving 0.0005″ to .001” of the “skin” within a tolerance of +/- 0.0002” for stainless steel as well as titanium, Nitinol and a wide variety of alloys. Electropolishing eliminates the need for additional metal finishing processes like hand deburring, tumbling, cleaning, and even passivation.
If your spec calls for passivation but you’d like to learn more about the superior results electropolishing provides, we can electropolish a sample of your parts for no charge and facilitate updates to your engineering change order (ECO) process.
Whether electropolishing or passivation is the right process for you, we offer the highest-quality finishing services. Our state-of-the-art 45,000 SQFT facility operates 3 shifts, 5 days a week. We offer expedited service, can handle parts of any size, and provide customized processing for every part, including custom racking. Start with a sample finish of your part for free.
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