Re: [CAD_CAM_EDM_DRO] Re: New guy with questions

In a message dated 12-Oct-01 10:46:02 Central Daylight Time,
johnhe@... writes:

> How does oil hardening tool steel work chemically? I know you can heat and
> dunk in oils instead of water for less harsh tempering.
>
>

John: It's not "chemically", but "physically". The alloy-molecules
"skruntch up" upon rapid-cooling, making alloy-bonds (whatever you call 'em—I
am not an eddikatid metul urge ist!) happen. Since the "oil hard" steel is
more expensive (to buy in rods and bars), it must have more magic in it than
"water hard". There is also "air-hard", but I don't know how it compares.

I THINK the oil-hard is more or less "ready to use" after quenching in oil,
whereas the water-hard is so brittle it must be carefully "tempered"
(re-heated a special controlled amount that takes years of skill at "reading"
color (redness) of metal, knowing when to stop re-heating, and HOW to
cool-down, properly. But I am NOT sure. When I need a "one-time" tool of
some kind, I often don't even pay much attention to which is which, and just
plunge the orange-hot tool in whatever's handy (my oil-bucket for this
doesn't evaporate as does water, so, often it's "just oil". This works, at
least for one-time, non-professional tools, so I retain ignorance!

Some metallurgist/tool-maker should answer this question for us all!
Well?????

Jan Rowland


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