5160 heat treat recipe's and the one brick forge

Josh Muller

Josh Muller

Joined
Jun 22, 2003
Messages
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alright... so i've been looking for a heat treat recipe for 5160 and have only seen one, and a few mentions of recipies for other parts of the heat treat cycle, mainly tempering. the only one i found thus far (im sure i wil find more as i search - im learning tons of valuable stuff by doing so... i really need to dig into my dieter mechanical metallurgy book for the information i need...) was posted by rlinger:

"I have noticed no benefit from deep cryogenically treating 5160.
-------------------
Here's one that worked well for a fairly large blade of 5160:

Preheat: 1150 F / 7 minutes
Austenitize: 1525 / 7 min
Oil Edge Quench
Temper: 400 / 1 hour
Temper: 375 / 1 hour

This blade took second place in a cutting contest of about 10 blades of different steels.

RL" (RLINGER)

my question is this - how can you determine temperature when using a one brick forge and propane?

are there thermometers available to test the blade surface temp? is it possible to use a high temp thermometer in such a small space, with a blade disrupting the airflow?
 
lol :D well, im gonna do that, but how do i tell the difference between 1150 and 1525/can it be done without a thermometer?
 
I got a multi meter from Harbor Freight for $20 on sale a while back, it goes up to 1000 degrees CENTIGRADE (which is 1832 dgrees Farenheight). It has a type K thermocople to measure the temp. I have also seen meters like this on ebay.

Here is one converter for Farenheight to Celcilus:
http://www.albireo.ch/temperatureconverter/
 
That isnt the one i got, i think they discontinued the one i got, but that looks like it may work. and it read farenheight also, mine only reads Celcius. :D
 
While heat treating is an exact science,metal working is a learned skill.One reason I regularly tell new makers to slow down is they don't yet know what the don't know.A good smith has learned to adjust his forge to attain different temperatures and atmospheres.He also learns what metal looks like at different temperatures.This skill comes with time and experience.It does not come fast,and it does not come without failures.Old apprentice smiths used to spend months just building and maintaining the fires.Then they would get to pick up steel and only pre-heat it.Finally they would get to forge....after they understood what hot steel was,and how it got that way!
BTW the HT info you printed was good for 5160.
 
The problem with a pyrometer or something in a forge is that there will be different temps in different areas, so you're not going to have exact measurements unless used in a nice, closed chamber. (like a brand-new evenheat oven -- man I want one.) Trying to "soak" or hold the blade in a forge might give you overheated areas. So.....

Get a magnet on a stick (like the automotive kind). Put the blade in your forge and watch the tip when it heats up and gets some color -- pull the blade out and let it cool a bit. But it back in. Repeat.

The point of this is to bring the whole blade up to full heat at the same time. It's slow, but you get a more even heat-treatment. As you can imagine, the thinner parts of the blade heat up quicker than the thick parts. They also lose their heat quicker. At the same time, the thicker parts heat up slower, but are also slower to lose their heat. If you keep up this slow heating, eventually, the blade will heat evenly. (I really hope this makes sense.)

Do this three times to normalize. Do the same heating on the final heat, then do your quench (probably three-quarter edge quench in oil preheated to about 140-degrees). Canola oil in a cake pan will work fine. Just make sure you have a lid to put out any potential fires. :) When the edge is darkened nicely and drawing out the heat from the unquenched part of the blade (which means the heated blade is starting to do the same to the quenched part) drop the whole blade in the quenchant. Temper as Linger suggests.

I hope this helps. There are a ton of ways to do this -- so this is just a suggestion.
 
I got one of Wayne Goddard's magnet on a stick but the first time I used it came out of the holder. It was held in with epoxy (I presume) and the heat made it release. Now I use one that is stuck on the side of my Don Fogg type upright forge.
Lynn
 
Ok, dumb question time. What is the reason or benefit of dropping the tempering temp to 375 for the second temper? Why not do both at 375?
 
In my clay supply catalogs there are nice digital pyrometers for less than $150.
They are rated to at least 2300f. If you're interested go to www.axner.com.
and look there.
I'm pretty sure though that you're not going to get a real accurate reading with all the turbulence created by the torch in such a small area.
Pat
 
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