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Passivating vs annealing

Can I replace an annealing process for 304 stainless with a passivating process for using humidifier tanks with pure water (D.I. or R.O. water)?

Alan Garnaat
- Three Rivers, Michigan, USA

Alan, they do different things. Annealing removes cold work, and will make the 304 more ductile, and restore non-magnetic properties. Passivation enhances the chromium oxide layer on the surface, and cleans off any stray iron particles that can be so troublesome.

I don't know of any nitric OR citric acid passivation processes that take place at the annealing temperature (about 1950 °F). . .

Good luck!

Lee Gearhart
metallurgist - E. Aurora, New York

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Alan:

Lee is correct. There is no passivation process that will replace annealing. Totally different process and purpose. The passivation comes after the annealing process.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois