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Rust formation on steel after electrolytic cleaning

June 2, 2013

Q. We are facing rust formation during alkaline degreasing of steel coil.
Steel coils are degreased in alkaline based solution We clean AISI 1010 Steel at this plant, and it is observed that after electrolytic cleaning certain parts of the steel has a formation of scattered rust, sometimes it is in the form of sludge can be removed by swabbing , but after drying and keeping it a longer time in resuls in tenacious rust particles. I would like to know what causing the formation of rust over a certain length of the steel, and this normally happens when the electricity is turned off.

Thanks in advance.

Sandeep Kumar
- Pune, Maharahstra, India

A. Hi Sandeep. Anything is possible but, because alkaline solutions should not cause rusting, my first guess is that the coils had that rust when your received them (possibly because of the way they were stored somewhere else, with water getting to only certain areas of the coil) and you didn't see it because they were coiled and covered with dirt and oil. Immediately after cleaning the rust might be soft due to the hot wet immersion, but hardens when it dries.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
June 3, 2013

November 9, 2013

A. Dear Sir ,

The presence of moisture in air immediately starts acting which causes this corrosion. When object comes out of tank you have to make it neutral (remove chemical effects) , and wipe/clean it with dry cloth . Then immediately make it dry by keeping it in sunlight or hair dryer [on eBay or Amazon] hot air and then apply preventive coatings (spray type available in market ). This final step is very important . Please see some videos on youtube.

Dhairyasheel Joshi
- Pune, Maharashtra, India

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