Decarborizing of 1095

M

mainemike

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Mar 28, 2014
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Hello, This is the first time I have posted to Blade Forums. I have been making knifes for a couple of years now. I got te basics down and I am always learning. I got some 1095 and I am trying to use it up. I have reviewed a lot of threads and discussions on the proper heat treat of 1095 on Blade Forums. I have a small Muffle furnace that I can control my temp pretty well with. I am battling De-carborization with the blades while I heat treat to harden. 1475 degrees F for 10 min, I tried less time, I tried 7 minutes, I tried 1500 degrees F, and still got some decarb. I use a anti scale coating and it helps but does not prevent it. I am afraid if I don't soak the blade long enough I will not get enough of the carbon into solution. I would buy some foil but I don't think I could get the blade out of the foil quick enough to get a good quench. Could I place a porcelain crucible with some wood shavings into the muffle furnace while I heat the blade? Would the carbon from the burning wood be enough to balance the atmosphere? I am just trying to get the most out of my 1095. Thanks.
 
Just my take on this, but I feel that controlling the atmosphere in the forge is pretty important, if you want to avoid scale buildup and decarb- it needs to be a fuel-rich burn, with some yellow flame coming out the door. Whenever I do demos or coach blacksmithing, it seems there's a tendency to run O2 rich for some reason.
 
This is not a worry. First off, scale and decarb are normal results from HT on a carbon steel.

Second, decarb is a problem with forging far more than a HT problem.

Third, at 1475-1500F and for 10 minutes, the decarb layer is very, very thin. It will sand off in the normal post HT finishing. Probably a few thousandths of an inch. The decarb layer, once formed, actually protects the blade from further decarburization.

Last, trying to hold the steel at 1500F in a small forge for 10 minutes is far more of a problem than protecting it from O2. The gas/air should be balanced to give a neutral atmosphere, and the forge dialed in as low as possible to just stay at 1500F ( which is nearly impossible with a venturi forge). Overheating will do many times more damage to the blade than a thin skin of decarb.


Wood chips and such in the forge are read about all the time online, but actually do almost nothing. Forget about that idea.

Anti-scale is a good thing for steels like 1095.
 
i disagree, a venturi forge with the proper nozzles and a needle valve is very easy for keeping a steady low temperature.
For example, my setup consists in a two burners forge; i can run 1 or 2 burners and i have 2 sizes burners. That arrangement allows my forge to run in neutral or slightly rich athmosphere from ht to welding heat and to be steady, with a very convenient fuel consumption rate.
I ditched the idea of rigging a PID into it since it is so easy to control that i couldn't see the need to complicate things for the sake of nothing.

to the OP: Is your muffle furnace an electric kiln? Antiscale compound will save you some cleaning time after ht.
 
Thank you Gentlemen. I have an electric muffle furnace. I work in a Wastewater treatment plant and I borrowed it from work. I wish I had a gas forge with a air adjustment. I would have a Carbon rich environment for sure. I guess I am going to do the best with what I got, until the 1095 I bought is gone. I am going to purchase some 1084 from NJ Barron.
 
The electric furnaces are the most difficult to run without athmosphere issues, but the antiscale compound should work, especially at those temperatures...something off?
You need to be sure that your muffle (probably used to determine the ash content in your plant, at a lower temperature) is still reading the correct temperature at the HT setpoint, and since the elements are buried (big lag and rebound) you should let it stabilize for enough time at the setpoint to avoid overshooting it and causing troubles.
1084 won't behave differently than 1095 in this regard.
 
stezann,
I was referring to a small forge that is not like yours. The simple 2BF and coffee can forges are not really going to work like your much nicer and more complex setup.

Mike,
I saw that you were using an electric kiln, but put the forge info in because this will be bread by many others who just use a simple forge. With your kiln, you should be able to do HT on carbon steel with no problem. My point was that the decarb layer is not an issue.
 
Hi Stacy, i worked my way step by step to my current setup :) my startup so-called forge, was actually very good to burn holes into the middle spot of the mistery steel bars we all like to start our journey with ;)
 
I just put charcoal fines in my muffle and have yet to have any real decarb, it definitely is a carburizing atmosphere cause the exhaust coming out of my muffle burns a nice red yellow, have done 1095, o1, and a2 with it just fine
 
Yes Sir, we use it to determine the amount of volatile organics in our sludge. Usually at a lower temp, I think around 600 deg F ? I usually place my blade in when I start the furnace. It heats up slowly, about 30 minutes to reach 1475-1500. I may over shoot a little? I let it soak at HT for 10 minutes. I have decreased the time to 7 minutes. Is the blade being exposed to long to temps between 600 to 1475 while climbing to the HT temp?? I was thinking of getting the furnace up to HT first and then placing the blade in and letting it soak for 10 minutes or more? I don't know, I have been able to sand and polish most of the scale and spots off of the blade, It just seems like a lot of black comes off when I quench the blade, excluding the anti scale compound. I work hard at making a blade and I just want to not see it be all in vain.
 
I should bring the muffle furnace to my buddies material testing lab and use his therm o-coupling to calibrate the temp. I am going by the needle gauge. The blade is red and non magnetic piece of mind I guess?
 
mainemike said:
I should bring the muffle furnace to my buddies material testing lab and use his therm o-coupling to calibrate the temp. I am going by the needle gauge. The blade is red and non magnetic piece of mind I guess?
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I would let the furnace getup to heat first, no need for hold times after you normalize for pearlite. I would just heat till non magnetic and no hotter.
 
JackPlane said:
I would let...
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Good evening, Jack.
You might want to check the date before responding to old threads. This question was almost 7 years old and the original poster hasn't been active for over 5 years. This is called necroposting and is generally frowned upon.
 
Welcome Jack. What weo said.
Also, fill out your profile so we know where you live. It helps with better answers and offers for materials and help.
 
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