CO2 in kiln for heat treat

A

AJH_Knives

Well-Known Member
I get lots of scale when i heat treat O1 and 1084. I have been thinking about injecting CO2 into my kiln while i am heat treating the steel. I have a digital controller on my kiln and it should regulate the temp just fine.. would this help with scale?

just thinking out loud... is this a bad idea?
 
First I've heard of either! I wonder if the stuff they sell for topping wines and such (its some heavy gas) would work? it might be easier to find?
 
Good question and I think you are on the right track. But no, I don’t think CO2 will do any good. It needs to be a combustible form of carbon.

I’ve used simple wood chunks (or charcoal) inside the furnace which will create a contained reduction atmosphere and help with scale.
 
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I've read that co2 is bad for the heating elements don't know why.
Argon and nitrogen are used argon is more expensive.
I think you just need to displace the oxygen with an inert gas.

Use in well ventilated area.
 
CO2 will still oxidize the carbon in the steel. CO, carbon monoxide, gives a better atmosphere. That's what you get with chunks of wood or charcoal inside the forge or inside a baffle pipe inside the forge. You can also get the same effect by finding the reducing level in a solid fuel forge or by adjusting the gas/air mixture in a propane forge. It's also what makes it necessary to have plenty of good ventilation while operating a forge.

Doug
 
I would say that argon would be the gas of choice, between my hobbies and my profession I deal with cylinders gases of Ar, Co2, and Co2/N mixtures and have experimented with many uses in the shop (purging Nelsonite containers and opened bottles of wine just a couple- oxygen is a pretty destructive gas). A TIG unit can run on Co2/Ar mixes or pure Ar, and although the Ar is more expensive I always get it due to the variety of metals I work with and the need for absolutely clean and flawless welds. The pure Ar leaves steel so clean you can hardly tell it was ever heated.

With an oven purged with Ar, you should have no problem meeting or exceeding the cleanliness and lack of decarb that I get with my salt baths, and that is the option I would direct most folks to if they were thinking of salts. For general knifemaking the purged oven is cheaper, cleaner and safer, with much less maintenance.
 
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