53353

Must we remove heat treatment discoloration on stainless steel? [Minnesota] 

October 14, 2009

My company does a little bit of heat treating in house. We heat treat 17-4 stainless steel (doing an H900 heat treat). Because we do an air cool we get a heat treat discoloration on all of our parts. Normally we remove this discoloration via a bead blast and/or polishing before we clean and passivate the parts. We are wondering if this is a necessary process. If we leave the discoloration due to heat treat on the parts is there a larger chance of rust and corrosion?

Thanks,

Mara Schwartz
Product designer - Minneapolis, MN, USA

Generally not, as long as a good passivation treatment is still performed, though most customers still want to see a discoloration-free surface even for parts that are destined to be buried inside a mechanism where aesthetics are not a concern.

Ray Kremer Stellar Solutions, Inc. McHenry, Illinois

If you can't use a mechanical method or a electropolish to remove the heat treat discoloration, and soaking in Oakite 90 does not remove all the discoloration, what other method is there that will not remove material? We place a very fine thread on the end of a part to aid in adhesive assembly and can not remove any significant material.

Robin Mahoney
- Memphis, TN, USA