Full Transcript:

What’s up guys?!?!?! This is Michael with Michael Talks Metal, back for video 105…… the third in our series on case hardening of steel.

In the last two weeks we have talked about nitriding and then carburizing. So what happens when we put the two together?  If your answer was carbonitriding, you are correct.

Carbonitriding is actually a modification of gas carburizing.

Like carburizing, we are adding carbon to the steel surface to achieve the desired hardness in the case but then we also introduce a nitrogen source during the carburizing cycle. Since carbonitriding is typically performed at the temperatures where the steel would be austenitized for hardening; an appropriate quench can produce a hardened part, ready for tempering to final properties.

Typical carbonitriding temperatures range from 1300 to 1650 deg F.

The nitrogen added to the steel at these temperatures does not form the thin nitride layer at the surface as in nitriding.  Instead the nitrogen diffuses deep into the enriched carbon layer and provides increased hardenability to the case.

This increased hardenability offers several potential benefits to any given part:

It could  provide a lower overall heat treating cost…….

Or  it permits using lower alloyed ( less expensive) steel……..

OR it could allow for a less drastic quench to minimize part distortion while achieving the desired hardness…..

The depth of penetration and the amount of carbon and nitrogen in the case depends on the temperature, time, and the amount of carbon and nitrogen made available to the part by the tightly controlled furnace atmosphere.

All this gets very complicated in a hurry so we leave the part and process design requirements to the professionals.

As we always say, part requirements and  specifications are critical; so  never forget to CHECK THE SPECS!!!! Michlin Metals is a full service aerospace metal supplier check the website at www.miclinmetals.com. If you missed last weeks video click here, and if you are still here haven’t subscribed please click here. Thanks for watching, this is Michael with Michael Talks Metal see you next Thursday, 10am, I’m out!