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-----Copper residue on steel bolts. Corrosion problem?
Q. Will a light, visible Cu residue on steel bolts (A286 material) eventually cause a premature corrosion or failure condition? We have some supplied steel bolts with a light copper residue left on them. The copper residue is the remains of copper coating which is used as a lubricant in a cold heading process. It is removed with a nitric acid solution. Some of the copper did not get removed. I am trying to find out if the bolt integrity will be at risk due to corrosion.
Thanks,
- Chicago, Illinois
2002
A. It depends upon the environment. In 99 of 100 cases, there may not be a problem. However, nobody wants liability for the 1 failure. Unless every bolt will be used in an application where copper is not a problem (e.g., with anti-seize lubricant ⇦ on eBay or Amazon [affil link] ), I recommend cleaning in 45-55 vol% nitric acid at 120-130 °F (QQ-P-35C (canceled) [link is to free spec at Defense Logistics Agency, dla.mil]C Type VIII passivation solution).
Ken Vlach [deceased]- Goleta, California
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