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Ferritic Nitrocarburizing

I have a customer pushing me to enter into this type of processing. We currently run continuous rotary retorts. I have no idea of where or how to begin. The process will be applied to pinion washers. I see the temperature ranges; however, I do not understand what type of quench medium is used? If we where to use a batch style furnace is it as easy as processing in the 1100F range and quenching in oil?

Jason Fettig
Commercial Heat Treat - Warren, MI, USA
January 13, 2009

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January 15, 2009

Nitrocarburizing, more commonly called carbonitriding will require temperatures up to 1750 °F in a furnace filled with carburizing atmosphere to which ammonia ⇦ this on eBay or Amazon [affil links] is added.

It cannot be done at 1100 °F.

Quenching in oil can be done within that furnace, or the parts can be later reheated in molten salt or otherwise and quenched to harden them. In most cases they'll also need to be tempered after hardening.

You'll need a furnace specifically designed for gas carburizing, and a source of carburizing gas such as an endo gas generator, or a blend of compressed gasses.

To buy and install the necessary equipment will cost in excess of $100K far a smallish operation.

If you are serious about proceeding, you can start by contacting manufacturers of carburizing furnaces, and you will need some technical help getting in operation. A furnace mfr *might* supply that help, or you could hire a consultant.

Many firms do carbonitriding; most of them are fairly sophisticated heat treaters with on-site metallurgical labs and tech experts. It isn't exactly rocket science, but does take some expertise.

There's plenty of info on the 'net.

Here's a basic starting point:

http://steel.keytometals.com/Articles/Art126.hto

Jeffrey Holmes, CEF
Spartanburg, South Carolina