On 01/08/16 12:57, Jim Wilkins wrote:
"Bob Engelhardt" wrote in message
...
Thanks for the replies, but if I still wanted to forge shape it, is
there a required process?
Rehardening and tempering it is the tricky part, and a very good
reason to grind a commercially hardened tool to shape instead. You can
practice on a discarded circular saw blade. I annealed one, cut it
into strips and rehardened a piece as hard and brittle as glass.

The few times I've hardened a tool I tempered it around 700F on an IR
meter, and if it was too soft to cut steel I rehardened it and
tempered cooler. That's less work than making another if it breaks
from being too brittle.
http://www.westyorkssteel.com/techni...-temperatures/

I think that chart only applies to plain carbon steels. I was just
looking for information about tempering EN24 (4340) and the information
I found gave a far higher temperature range for tempering, the chart
giving the various properties curves and temperatures and ranged from
450C to 650C and needed a longish soak time compared to carbon steel. I
made a few replacement pipe cutting rollers from EN24 and when hardened
and tempered according to the carbon steel chart they crumbled, now I
need to take the remaining one and temper according to the new
information and see how it performs, fortunately I have an accurate
temperature controlled furnace. Just got me thinking that if the alloy
effects the tempering temperature that much then trying to temper an
unknown alloy is likely to be hit and miss.

Regarding the IR temperature reading how did you assess the emissivity
in order to get an accurate reading from the meter.

http://www.ctmuzzleloaders.com/ctml_...tempering.html
The thermocouple adapter on his DVM looks like an expensive Fluke
80TK. The inexpensive TM-902C thermocouple readout I would have
suggested is out of stock at Amazon. Omega's GG-K-24 thermocouple wire
is a good choice to make your own. Wood stove gasket cement will bind
the cut ends of the insulation. Do you have or know someone with an
acetylene torch to fuse the end?
http://www.omega.com/pptst/XC_K_TC_WIRE.html

When you heat the end with a torch to reharden it part of the shank
will lose its temper. Perhaps that won't matter for a prybar for
molding. Good luck with it.
--jsw