Subject: Re: Heat treating steel

From: [email-masked] (Rick Cook)
Date: 19 May 1996 07:20:50 GMT

Alden  Hackmann wrote:
>First, how does someone like me (lacking a heat-treating oven or the
>resources to obtain one) do any heat treating at all?  I have a blowtorch,
>which seems fine for heating the piece to cherry red.  After quenching,
>attempts to heat the piece a little more gently have not been very
>successful.  What am I doing wrong (besides not buying an oven...)? 

Get yourself a plate of mild steel, fairly thick and big enough to set the
work on. Heat the plate and place the object on the plate. Note that this
only works if the object is of fairly uniform thickness or if you want to
only temper part of it (such as the edge of a blade.) For working edges of
tools, I usually just polish the part, heat the thicker portion and watch
the color run out to the working edge.

--RC

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From: [email-masked] (Ron Hock)
Date: 21 May 1996 15:50:42 GMT

>To judge "cherry red" on drill rod, I heat until it becomes non-magnetic, 
>then get it a "tad" hotter.  The trick part is holding this temperature 
>for at least 5 minutes (for small pieces); 20 minutes is better..

The amount of time required at critical temp (1450-1500F for O-1) depends on
the thickness of the stock. Since the carbon is "as if in solution" at the critical temp,
it can and will migrate to the surface and be seduced away by  all those fast and 
loose oxygen sluts. Therefore, we want to hold the metal at that temp no longer than 
needed to ensure the transformation to austenite, loosing as little carbon as possible. 

In my experience, once the 
steel ceases to be magnetic, it's ready. Do allow it to go slightly above that temp to
be sure that you have enough time to reach the quench tank before it drops below
critical.

>I think the crayons work better in an oven (which I don't have, either.)

I tried the crayons, too. I hated them for the same reason you do and never used
them again. If you're tempering in the ktichen oven, you can use a little pile of the 
crayon crumbs as an indicator for the low-temp draw. With O-1 for  Rc62, go to 325F.
Of course, you'll need a 325F crayon...
Good luck.

Ron Hock ([email-masked])
Hock Handmade Knives
http://www.mcn.org/a/rhock/hockhome.htm