Question concerning soak time with basic set-up

samuraistuart

samuraistuart

Joined
Dec 21, 2006
Messages
3,158
I'm hoping you more experienced heat treaters could guide my thought process here. Just some quick background, I'm still very new to knifemaking, stock removal, made about 5 so far. I live in an apartment, so equipment and tools are minimalist by necessity. I've been working with 1084/1080+ and some W2. My heat treat set up is a "paint can forge" (layered with inswool/satanite) burning MAPP in a swirl pattern. I totally understand that this type of set up is OK for 1084, I get to 1475 and quench. But other steels this set-up is somewhat lacking. W2 needs a little bit of soak, as does 1095, and I understand O1 REALLY needs some soak time. So, obviously, having a set-up like I do makes "saok time", uh.....um.....er........difficult.

While watching vidoes of knifemaker's heat treating in their forges (not digitaly controlled ovens), I see them pull the steel out, put it back in. Pull it out, put it back in. Pull it out, put it back in. I assume they are trying to make sure heat is distributed evenly across the blade. Could this action be performed in our simple "forges" in order to control heat during the "soak time"? I'm hoping that once a blade has reached, say 1475 or whatever the recipe calls for, you could cycle the blade in/out of the forge to keep it at that temp. If you just left it in there, it will get way too hot. The chamber in my paint can forge is rather narrow, so heat can build up big time. I also suspect placing the nozzle farther away from the entrance hole might help to regulate temp, as well as the control knob on the torch itself.....to some extent. I'm hoping that you can keep a blade at a particular temp using this method of cycling it in/out of your forge, and hoping the community could comment on this for me! Thanks in advance!!!
 
Usually the in and out is just that, checking color and its even spread. When I HT in my forge, I get the interior nice and hot then back down my pressure to a good management level.
You should be able to maintain a good heat by passing the material in and out, even some of the best forges have colder spots that have to be worked around, plus there is the different thickness aspect that has to be dealt with. Make sure your edge is primarily the right temperature by color, magnet, or better yet by thermocouple etc. If you are getting a nice even temp across your whole blade edge you will ultimately be ok. Typically if you are HT the whole piece, some moving around is gonna be necessary.
As for soak directly, I try to maintain mine more with the burner than with in and out of the forge...
Hope that answered your question. Basically though, its just a matter of reaching the appropriate temperatures (up and down) at the appropriate time for the specific steel.
 
That's a god question, i have the same doubt!
I think is very dificult keep the same temperature necessary for a soaking time in a D2 steel, about 15 or 20 min in a high temperature, for example!
Actually i use just simple steel like SAE1070 and SAE5160, but i want to use, O1, 52100, D2 and others...
Even the 5160 steel needs soaking time, i try to do it like you discribe here, but i don't trust it works...
Here in Brazil a oven with temperature control is very expensive!
 
Last edited:
Stacy recently described the proper use of a muffle pipe in another thread. This is the way to do a soak in a propane forge. I tried a piece with flux on it, and most of the blade came out well, but there were a few areas of deep pitting from decarb. Make one of these http://www.arscives.com/bladesign/forge.tutorial.htm and use a muffle pipe, or make an electric PID heat treat oven. The simplest solution is send it out for heat treat.
 
I meant to add, I do use a muffle (tent) not pipe. Placement of the thermocouple in the muffle is the key to monitoring that temperature. My muffle is simply 14ga steel bent in a low arc with steepening sides. I get good even color and temperature with that method. Its is almost impossible to soak, even when adjusting the burner, without one and getting the whole work area uniform.
 
I just wanted to kinda let ya'll know how my heat treat went yesterday. I was using the recent W2 being discussed, and sure enough there are problems with this batch of steel....but that's another topic. W-2 requires a soak time of 5-10 minutes, and I've been worrying about getting that done with my little paint can forge. However, by adjusting the flame knob down a bit, after temp inside the forge was reached, and cycling my blade in and out of the chamber, I was able to keep the blade at a given temperature.....no problem at all. I had clay coated the blade, the edge having a thin wash.....and I did this in dark. I had a magnet handy, and was easily able to determine the color of non magnetic....and then went a few shades more. Did a brine quench. The edge is definitely screaming hard....but the anomolies documented by another knifemaker with this batch of steel indeed presented themselves on my blade as well. Oh well.......it'll be my shop user. Thanks, guys, for the great info!!
 
Good go. Glad to hear it worked out minus the steel issues... Sucks to put in that work then discover all that work was hosed by a bad batch of steel.
I got bit by a fleabay steel seller advertising this stuff as 1095. I should have checked it myself, and it did work funny and had an odd color but went ahead. The finished blade cracked like porcelain skin when quenched.
I now sacrifice about 2" of every bar with a HT and destructive test...
Would hate to crap away all that work again...
 
You must log in or register to reply here.
Back
Top