Re: [CAD_CAM_EDM_DRO] Re: New guy with questions

>
> I believe oil hardening steels work just as high carbon steels for
> hardening. The oil hardening steels however have alloying elements
> which allow it to fully harden with a slower quench. The quench is the
> dunking in water or oil. There are also air quenching steels which
> harden in air.
>
> There is a structural change of the steel, crystaline latice structure,
> when hardened. I'm not sure if this is considered chemical or not. I
> also do not fully understand how the alloying elements effect a steels
> hardenability.

I'm not real solid on this, but when you heat steel up the alloy phase
structure changes. As it cools, some of it changes back. By
quenching it, you freeze it before this process can run to completion,
leaving more of the form that manifests itself as hardness.

It seems to me that an oil quench steel would be chemically formulated
in such a way that the phase structure doesn't tend towards the soft
form as quickly, so that it is still possible to trap some of it in
the hard form even when cooling more slowly in oil.

I guess air hardening steel is really resistant to changing back to
the soft form, so that it can be 'quenched' in air?

Contrast any of these to annealing, where you slowly cool the steel by
insulating it or even gradually ramping down the heat. That would
allow all of it to change to the soft form before the temperature gets
so low that the structure is fixed.

Chris