Help with heat treating 1084 in Paragon

[SkagSig40]

Hello Gentlemen,
I'm a new maker and I bought a used Paragon SC2 from a friend who is a knife maker. This is a little tiny kiln designed for jewelry but will work for small knives requiring heat at or below 2,000 degrees. I can treat all my 10" and shorted blades till I progress to longer ones. I'm wondering a few things about 1084 I got from Aldo. He said to normalize it at 1600. My questions are:
* How long do I hold the steel blade at 1600 for?
* Does it matter how fast the Paragon heats it up to 1600?
* Is cooling time critical? Can I simply open the Paragon door, grab the blade and let it cool on my concrete garage floor? Wave it around in the air till it is cool to the touch?
*When doing the actual heat treat treatment, I'm programming the Paragon to 1500 degrees. Once it is there do I need to soak/hold it at that temp for a certain time? Again, does it matter how fast it heats up to temp?
*Do I then just open the Paragon door, grab the blade and immediately stick it in my canola oil till it is cool?
Anything else I should do? Thanks for the help!!!

 

[kuraki]

* How long do I hold the steel blade at 1600 for? 5 minutes or so should be fine
* Does it matter how fast the Paragon heats it up to 1600? Only if you're in a hurry because your knife shouldn't be in there while it's heating up
* Is cooling time critical? Can I simply open the Paragon door, grab the blade and let it cool on my concrete garage floor? Wave it around in the air till it is cool to the touch? Cooling in open air is probably a best practice. In front of a fan works. Sitting on a grate that allows airflow works.
*When doing the actual heat treat treatment, I'm programming the Paragon to 1500 degrees. Once it is there do I need to soak/hold it at that temp for a certain time? Again, does it matter how fast it heats up to temp? For 1084 a soak isn't required but in an electric kiln it's probably a good idea to give it a few minutes after it gets back to 1500 to make sure you've reached your target temperature through the entire thickness of the blade.
*Do I then just open the Paragon door, grab the blade and immediately stick it in my canola oil till it is cool? Yes, agitate it in the canola with the edge, not across from it. You can pull it out before it's cooled passed 400f and straighten it while it's still rubbery, or you can cool to the touch. The important part is over once it's cooled passed 900f.
Anything else I should do? Thanks for the help!!! The 1600f normalizing cycle will break up coarse spheroids but will result in larger than desirable grain size. You can reduce the grain size by thermal cycling at 1550, and 1500 and 1450 the same way you normalized, cooling to black between each heat in open air. This will reduce the grain size by creating new grains inside the boundaries of the larger ones.

 

[SkagSig40]

Thank you very much! When you say my knife should not be in the paragon while it's heating up, I was under the impression you put your blades in and then heat up to temperature and that way you know your steel is fully heated. If I am supposed to put The blade in once the oven reaches the 1600° mark, how will I know when the blade is 1600°?

So let me see if I got the thermal cycling process correct. I Heat the 1084 blade to 1550, take it out of the Paragon and let it cool to room temp. Re-heat to 1500, let cool and finally re-heat to 1450 one last time and cool. Then I can do the heat treat at 1500 and quench in canola. Only question is when exactly do I put the knife into the Paragon? While it is heating up or after it reaches 1500 and then insert the knife? If it is after the Paragon hits 1500, how long will it take for the knife to reach 1500 and how will I know when it does?

 

[kuraki]

Thank you very much! When you say my knife should not be in the paragon while it's heating up, I was under the impression you put your blades in and then heat up to temperature and that way you know your steel is fully heated. If I am supposed to put The blade in once the oven reaches the 1600° mark, how will I know when the blade is 1600°? You put the blade in, when the controller indicates you've come back up to temperature, and then you wait. The time is dependent on your kiln, the size, how much mass is being heated, etc. For a smaller blade, a few minutes is enough. For a different steel that requires a "soak at temperature" that time would start AFTER you've estimated the blade has reached temp all the way through. This is part of the equation that makes giving people black and white text book answers very hard, and why heat treat discussions often result in people qualifying their answers with "but you have to test yourself." Because you do. None of us know the exact conditions your kiln is operating in. In general, with a forgiving steel like 1084, and a kiln, and a smaller knife, it's safe to say a few minutes after it's climbed back up to temperature is fine.

So let me see if I got the thermal cycling process correct. I Heat the 1084 blade to 1550, take it out of the Paragon and let it cool to room temp. Re-heat to 1500, let cool and finally re-heat to 1450 one last time and cool. Yes, that is thermal cycling. You do this after the normalizing cycle. People often confuse the whole process as "normalizing" or skip the normalizing cycle because they're so similar in method. 1600 cool to black, it's normalized. 1550 cool to black, 1500 cool to black, 1450 cool to black now it's thermal cycled for grain reduction. Heat to austenitizing temperature, 1500, and quench. Those thermal cycling temperatures vary depending on the steel and the individual's own testing.

Then I can do the heat treat at 1500 and quench in canola. Only question is when exactly do I put the knife into the Paragon? While it is heating up or after it reaches 1500 and then insert the knife? If it is after the Paragon hits 1500, how long will it take for the knife to reach 1500 and how will I know when it does? Same as above for normalizing.

The only time you should be putting a knife into the kiln before it's reached austenitizing temperature is when that particular steel's heat treat protocol requires a pre-heat and ramp to temperature. And even then, you shouldn't be placing it in until it's at that first stage temperature.

Grain growth comes from time and temperature. More time, higher temps, bigger grain. Allowing the blade to spend so much time in the kiln is just going to ruin all of the work you did thermal cycling. There may be other reasons not to do this, it's discussed often.

 

[JG Custom Metal Works]

Another thing to consider is heating your quench oil. This prevents a “vapor jacket”from forming around the blade, preventing the oil from reaching the blade in a way that cools it down fast enough. I’m not sure if you need to do that when using canola oil. I use McMaster-Carr’s 11 second quench oil with 1084 and heat it to 130 degrees prior to quenching my hot knife. As far as heating the oil, I use a digital laser thermometer that takes temp by laser, as opposed to having to stick the thermometer down into the oil. They can be bought for $20 or so at Harbor Freight. I heat my oil by storing it in a metal ammo can and placing it on a cheap hot plate from Walmart. You can also heat up a piece of steel(in a forge or with a torch) and then stick it in the oil.

Again, I don’t use canola oil for quenching 1084, So someone might chime in about whether to heat it or not.

Always wait until the kiln is up to temp before putting the blade in. Kevin Cashen, who is a VERY reliable source from heat treating information, says to let 1084 to soak for 10mins at temp before quenching. So that’s what I go by. Here’s a couple articles he did about 1084 specifically:

http://www.cashenblades.com/steel/1084.html

http://www.knivesby.com/knifemaking-Kevin-Cashen-treating-1084.html

 

[samuraistuart]

When using canola, I find it works best warmed up. 130F is good. If using commercial quenchant, follow their instructions.

Yes, another voice here saying that the blade should be put into the kiln only after the kiln has reached target temp, and settled there for a while. I usually wait about 20 minutes, just to make sure there are no temp overshoots and large swings in temp. A heat sink source helps with this, if your kiln does that.

 

[Busto]

It is always a good idea to allow the Kiln to reach target temp and sit for a while...It's the Thermal mass the bricks are absorbing that give the best heat treat not just what the coils produce as registered on the controller. I allow my Kilns to soak a minimum of 30 min. after reaching temp (for simple steels) Ramping from that soak time is much faster also.

 

[SkagSig40]

Thank you very much everyone! So correct me if I'm wrong, once the Paragon hits what ever temp I'm needing, I put the knife in and in about 3-5 minutes It will be at the indicated temp(1450/1500/1550/1600). Then I let it soak for another 10 minutes? Do I wait this 10 minutes each time during the normalizing cycle, all the thermal cycles and the actual 1500 degree heat treatment?

 

[Stacy E. Apelt - Bladesmith]

The HT sticky has all this and the explanations of what is happening. I suggest you read them to understand what you're doing during HT.

 

[SkagSig40]

Thanks Stacy, I see it and will read up through all of it. I skimmed through the thermal cycling and did not see an answer for "So correct me if I'm wrong, once the Paragon hits what ever temp I'm needing, I put the knife in and in about 3-5 minutes It will be at the indicated temp(1450/1500/1550/1600). Then I let it soak for another 10 minutes? Do I wait this 10 minutes each time during the normalizing cycle, all the thermal cycles and the actual 1500 degree heat treatment"? regarding 1084. Thanks for the help!