What’s up guys?!?!?! It’s Michael with Michael Talks Metal back for more what? Well Talkin of course….what else do I do? This week our topic is the first of several on the case hardening of steels. A primer on the basics of selectively heat treating the surface of parts.
First up is the process of nitriding of steels like last week’s alloy 135M. If we add nitrogen to the surface of an alloy steel part; we can form a thin but very hard and wear resistant layer.
That is a useful thing to have on the contact areas of gears and bearings.
Several methods can be used to create the nitrogen enriched surface
If we heat the part to sufficient temperature in an environment high in nitrogen, it will diffuse into the steel surface. Elevated temperature is required to achieve an acceptable rate of diffusion and amount of nitrogen that can be absorbed.
Parts can be heated in a nitrogen gas environment or in molten salts containing the nitrogen. Typically temperature is in the range of 950 to 1050 deg F.
Ion or plasma nitriding occurs in a vacuum chamber where an electrically charged plasma of nitrogen ions are accelerated and drawn to the steel surface.
Often the parts are heat treated prior to nitriding to create strength and toughness in the core. The intended nitriding temperature would be the minimum tempering temperature in any core heat treatment.
Nitriding can be applied to essentially any steel and many other alloys. Since it forms a very thin layer, it is typically the finished surface.
Nitriding occurs at relatively low temperatures which makes distortion much less of a problem than in many of the other surface hardening methods we will be discussing in later videos.
Details of these processes are quite complicated so part requirements and specifications are super important so don’t forget to: Check the Specs!!!!
That’s it for today folks! Thanks for watching don’t forget that if you have more questions you can visit our website www.michlinmetals.com – missed last weeks video? Click here. Still here and haven’t subscribed? Click here. Thanks for watching, this is Michael with Michael Talks Metal, see you next Thursday 10am. I’m out!