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View Full Version : Argon purge for oven, What do you think?



JDW
08-15-2010, 07:36 AM
I have ask this on another forum a couple years ago, with little responce, so I forgot all about it, until now.
The question is, has anyone ever thought about, using a flow meter on an Argon tank and piping it into an oven, to remove oxygen from the oven while heat treating. I have thought about this, and it seems like the heat treat ovens are sealed prety tight, so as not to loose alot of the argon, and once it is purged, it should only require a low flow to keep it oxygen free. Have I just completely lost it? or does this sound like it would work, and be a benifit? And if it did keep the oxygen out, what, if any ill effect could it have on the heat treat oven, or the steel? I know that Argon is used in Tig, and Mig welding to keep the elements of the atmosphere out of the weld zone, and should do the same in the oven. What do you Knife Dogs think?
Dale

Wayne Coe
08-15-2010, 07:50 AM
How 'bout trying it and reporting back about your results?

Bob Warner
08-15-2010, 07:57 AM
Gene Osborn used to do that. Also, Paragon heat treating ovens now have the piping as an option.

I talked to them about it and was told that you have to kinda blast it in the very beginning to purge the oven and then just trickle it from then on to keep it purged, sounds like a pretty good idea.

If I were you I would contact Gene Osborn of Centercross and get his opinion on this because I think he stopped doing this.

Bob

JDW
08-15-2010, 08:09 AM
Wayne, I may do that, but I thought if someone had already tried this, they might have some advice, or if it was a waste of time. I do have a flow meter, but would have to come up with the Argon, not hard to do, except for the cost, in my area you have to purchase a 25 year lease to get tanks or buy them. If I do try this, I will report how it goes, along with the setup used.

Bob, thanks for the input, at least I know that I have not completely lost it. Do you have contact info for Gene? you can e-mail it if you don't want to post it here.
Dale

Les Voorhies
08-15-2010, 08:14 AM
I did it with my evenheat a few years back and I wasn't happy with the results. I went through my 75CF tank in record time and the blades didn't seem near as clean as when BOS does them. I think part of the problem was not keeping the argon on them while they cooled (I wasn't plate quenching back then), but I was using so much argon I just couldn't keep doing it.

JDW
08-15-2010, 08:24 AM
Thanks Les, if it eats up Argon, that would be to costly for sure. I was thinking mostly to use it with O1, so it would be a quick trip to the oil tank, but if it takes alot of flow to keep the oven purged, it would be a waste of time. But in case I want to try it, what did you use to pipe in to the oven, I was thinking stainless steel tubing.
Dale

Les Voorhies
08-15-2010, 08:45 AM
I used a stainless tube, drilled a hole in the side of my oven toward the back. One of the problems I found was the soak times for stainless (you might not have that problem with O1), I had to soak at preheat and at the final temp, thats 40 min minimum, plus the time it takes to get from prehear temp to hardening temp, and if you do more than one blade at a time you need to take them all out at once or flood the oven heavily each time you open the door. Keep in mind that I didn't ask anyone who might know about these things how to do this, I just figured what needed to be done and tried it a few times... so I could be missing something.

Wayne Coe
08-15-2010, 09:18 AM
Dale, It seems that there is a lot of information out there if you just ask, at least here on Knife Dogs.

You were correct: There is no reason to go out and reinvent the wheel...or heat treating.

JDW
08-15-2010, 09:19 AM
Les, the multiple blades is where I have an issue with O1, the first blade is always prety clean after the quench, but the next one, after the oven has been opened to remove the first blade, will have prety heavy decarb, but it sounds like the Argon purge might not help that much on multiple blades.
Did you have any trouble drilling through the brick lining?
To conserve Argon, I thought about turning on at around 1200 degrees, or whatever would be just below carburizing temp, but don't know if that would be good or not. I may give it a try, just for an experiment, but will stay with foil for stainless, and other air hardening steels.
Dale

Les Voorhies
08-15-2010, 09:37 AM
Did you have any trouble drilling through the brick lining?
To conserve Argon, I thought about turning on at around 1200 degrees, or whatever would be just below carburizing temp, but don't know if that would be good or not.

I didn't have any problem drilling the hole (it's still there, open to this day :) ) and 1200 is about where I turned it on.

clancy
08-15-2010, 11:16 AM
I work in semiconductor processing and we have done experiments with N2 purges in ovens. It doesn't work as well as you would think. Using a quarter inch line with the N2 flowing out at a high rate we were able to drop the O2 level from 20% to 19% in 15 minutes. The oven was all stainless with gasket seals, the exhaust line was only about 3/8" so we expected an inert environment. Opening the door brought the O2 level back to 20% instantly.


Putting everything into a glove box with routine leak checking worked, but we found that a vacuum oven worked even better.

ernie

JDW
08-15-2010, 07:21 PM
Thanks Les, it looks like we were both thinking the same way, on when to turn it on.

Thanks Ernie for the input, sounds like it may be a waste of time.

Dale