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Galvanic Corrosion during Copper Strip

We've recently discovered pitting/corrosion defects in a large variety of parts after copper plating - heat treat - strip processes. After doing some forensic analysis, we are leaning toward the conclusion that these parts fell victim to galvanic corrosion because they were all stripped on a week when pH in a strip tank was known to fall below the spec limit. The data we've gathered supports this conclusion, but it is troubling to me that we did not catch these defects until nearly 1 month and a couple of machining steps later. The pitting on these parts was obvious when it was reported and I'm not sure how it could have been missed. My question is: Does galvanic corrosion get worse over time even after being removed from the strip tank?

Kurt Nielsen
continuous improvement - Fort Worth, Texas, USA
July 19, 2011

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Hi Kurt,

It really depends how well protected your parts are after stripping. If the material is a low alloy steel and you don't protect the parts during transit and interstage between machining operations then any initiated corrosion will only get worse.

Brian Terry
Aerospace - Yeovil, Somerset, UK
July 22, 2011