Too Hot Before Quench?

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paintfool

Joined
Sep 7, 2004
Messages
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What exactly happens if you take the blade up too hot before quench?
I've not been able to get my O1 blades past non magnetic evenly, without taking them up a bit hotter.
Are there any negatives by doing this?
I've done 2 blades this way so far and they both seem to be about right.
As well I tested some scraps this way and snapped them off in the vise, the grain seems to be small, tight, and kinda silky looking:footinmou , and that's exactly what I want, correct?
TIA Steve.
 
The fracture surface should have a fine texture .A course texture means that you have overheated the steel and it will be brittle.You might change your proceedures to heat the blade more evenly, how are you doing it ??
 
Are you using a digital oven? How do you know it is too hot? How long are you soaking the blade?
 
I agree with Bruce, good control is the key. The major problem with going to hot is grain growth which equals weak steel across the board. With something like O1 you really don't want to overheat it- it doesn't like it, trust me ;) . Another problem is moving carbon into places that you don't want; this could also be a problem particular to O1.

The good news is that it is hard to have these problems of you have good temperature control. Steel is meant to be held for a certain time at temp to get everything into solution, if you temp is tight you can hold it there all day with little to worry about. Folks who heat treat in a forge (relax boys, I did and still do occasionally) do not have the luxury of evenly soaking for say 5 minutes at 1475F. to pull everything into solution, so we compensate by going for shorter times at higher temps. this runs the risk of the problems mentioned above.

What I like to do, if using a coal forge, is to build a firebrick tunnel over my fire and then use it like and oven to heat treat in. This allows for an even heating at temperature without having to over cook any part. You may also have a situation where you need to match your fire to the size of the blade you are doing, and of course, practice, practice, practice...

P.S. if you are doing a bowie with a torch, do yourself a favor and build a good fire somewhere to heat the entire blade ;)
 
I'm using a one bricker', well more like a 2 bricker and propane with an oldschool nozzle, I'm not sure what type it is, all I know is that it puts out a lot more heat than anything I can find in the stores (propane wise)

anyway, I can get the whole blade up to and past critical temp no problem, I've been taking my time and moving the blade in/out slowly, it probably takes about 10-15 minutes to get it heated up, then I keep it there for another 2-3 minutes and quench in warm oil. I wouldn't say I'm taking it WAY too hot, but by color it's hitting orange before I quench.

all my test pieces have come out the same way with a nice small grain so I guess it can't be doing too much harm. :confused:

Steve
 
What Bruce and Kevin said.

Additionally, with propane, many people are now constructing multiple forges for specific purposes. A welding forge run with a big burner at high temps is a tough one. But a dedicated heat treating forge, powered by a smaller burner will make things more controllable. It's not a salt bath, but with a digital pyrometer and some practice you can get very good control and even go for some soak time. Finally, putting a piece of pipe in your forge--sort of like what Kevin suggested with the fire brick--will give you a more even heat with less oxidizing. Cap off the back end of the pipe and throw a chunk of wood in for an even more reducing atmosphere.

That said, I want salts by summer ;)

John Frankl
 
No, that'd be a sign of oxidation which means there's probably a decient amount of decarb you want to be sure to grind off.
 
I built a Reil freon tank forge and was having similar problems. My solution was similar to Kevin's. I bought a 2" diameter iron pipe that was threaded on one end, put a cap on it and layed that in my forge. The burner blows on the pipe, which eventually heats up pretty evenly. Since then I've had much better luck with more even heating.

One major caveat about this, it took quite a while to burn all the galvanizing off the pipe, so if anyone else tries this look for non-galv pipe! Zinc is bad for you (but it does burn with a pretty green color).

Ah, but I only have about six more months of saving change before I have enough for a nice digital oven... :D
 
ddavelarsen said:
I built a Reil freon tank forge and was having similar problems. My solution was similar to Kevin's...:D
Click to expand...

The pipe thing wasn't my idea. I like a brick tunnel over the forge fire where the heat source, and benficial atmosphere, is in there with the knife. I have to be honest that I do not care for the steel tube in the gas forge concept (tried it and did not like it for various reasons that I will spare you from, since I am not saying it is wrong it just isn't right for me). Although I do most of my work in a gas forge, if I must heat treat without my salts my prefered method is a coal forge. My problem with using my gas forge is that it accentuates the issues that my salts completely eliminate. Believe it or not the gas forge heats too evenly :confused: , with high heat coming at the entire surface of that blade all at the same time the tip and edge come up to temp long before the ricasso or spine get there, often the best way to compensate is to move the blade in and out of the burn chamber and allowing the atmosphere to oxidize and decarburize the snot out of it. In a coal forge I can maintain a competely carburizing atmosphere, without blowing heat all over myself. I can lay that ricasso ans spine in the fire and gently bring them up to temp first while keeping the tip out of the heat. Control of heat increase and decrease is instantaneous and absolute. I have managed to produce blades austenitized in a coal fire that were as clean as those done in my salts.

Well that was kind of a long winded way of saying that I suggested a closed fire in coal and not a tube in a gas forge... sorry about that :rolleyes:
 
I'm just about finished of it now, it's a large camp knife, I guess I'll be able to tell when I put an edge on and put it to some use.

Is having a nice hammon a false sense of a job well done? it's got a really distinct line.

I'll post some pics when it's finished and you guys can judge for yourselves.
Steve
 
ddavelarsen said:
Ah, but I only have about six more months of saving change before I have enough for a nice digital oven... :D
Click to expand...
Me too Dave. :D That's on my next big purchase list.
Scott
 
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