Metal finishing Q&As since 1989

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Removal of heat treat scale from martensitic tube

My company is currently looking for a solution to a very unique scaling problem. We wish to remove the scale imposed on both the inside and outside of a martensitic steel tube of non-constant cross-section by a high heat and water quench process. Is there a particular process that readily lends itself to this application?

Russel Kozak
- Northville, Michigan
2003

There is a possibility that you could run them thru a vacuum furnace or a furnace with a reducing atmosphere, but I kind of doubt if you can go to a high enough temp. It is worth looking into. There are acid pickles that may reduce some of it. There is a 3 and a 4 step chemical process for it (McGean-Rohco is the one that I used), but it is less than optimum if the part is really blue or a dep black.

James Watts
- Navarre, Florida
2003

Conventional pickling with either sulfuric acid or hydrochloric acid will remove heat-treat scale. Less aggressive acids like citric, oxalic, phosphoric, etc. will not completely remove anything more than mill scale.

Toby Padfield
- Michigan
2003

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Best to avoid scale formation. A. O. Smith has a water-based coating Ceram-Guard 96 which protects metals from oxidizing to 2300 F and then spalls upon quenching. Let us know any results (I only know about from an ad).

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2003