On 7 Jan 2011 02:58:48 GMT, "DoN. Nichols"
wrote:

On 2011-01-06, sarah123 wrote:
responding to
http://www.rittercnc.com/metalworkin...nt-126232-.htm
sarah123 wrote:

Karl Townsend wrote:

[ ... ]

I'll heat 1475, quench in oil, temper at 950.

[ ... ]

Did you try this heat treatment as mentioned above? Did it work as
intended? How long did you hold the part at 1475 F, quench in oil, and
temper at 950 F?

I've lost the original question, but in general, you need to
read the specs for the metal in question to determine these factors.

Typically -- how long is determined by the thickness, usually
specified as "N minutes per inch of thickness". The temper is also held
for a time proportional to thickness (to allow the full piece of metal,
from outside to center to reach the desired temperature).

And the *temperature* for the tempering is determined in part by
the desired final hardness.

If you can get the book from the manufacturer, it will have good
information on this.

I've not hardened 1095 -- but most recently hardened D2 (an air
hardening steel which still requires a few tricky steps during
hardening.

Good Luck,
DoN.

As an apprentice boy one of the things we learned was how to make our
own tools and particularly for boring bars it was common to find them
in the shop, mainly bars made for some particular task that a
commercial bar wouldn't handle.

The accepted technique was to forge the bar to shape, rough grind it
and then harden and temper. As we had no ovens and did it all in a
forge the hardening was by heating to "cherry red" and quenching and
then polishing and tempering to a "light straw" color and re-quench.

An accomplished tool maker could harden and temper in a single heat by
quenching the cutter portion of the tool and then quickly hit it on
the grinder (to see the colors) and let the colors run down the shank
- from the unquenched portion - and when the correct color reached the
cutting edge stick it back in the water.

I am certain that we never got as constant result in dong it this way
but I will say that it was a common method for making tools for a
hundred years or more.


Cheers,

John D. Slocomb
(jdslocombatgmail)