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topic 5572

Passivation of 440


What is the best passivation process for 440c?

Dave Mortenson
Pullbrite, Inc. - Fremont, California USA


Electropolishing is considered the best way to passivate stainless steel. What particular application did you have in mind?

tom pullizzi portrait
Tom Pullizzi
Falls Township, Pennsylvania


We use the Type 8 formulation found in AMS2700 [link by ed. to spec at TechStreet], which is the same as the Type VIII found in the olde QQ-P-35 [link is to free spec at Defense Logistics Agency,]. 45-55% nitric acid in water, 120-130F, for 30 minutes minimum. We don't use a chromate dip afterward.

lee gearhart
Lee Gearhart

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