Heat treating in a kiln

Jonnymichigan

Active Member
Ok so when you guys heat treat I'm sure you know when you out the blade in the temps drop and you have to wait 5-10 min for the temp to get back up to targets temp. Is that long enough for the steel to soak and be that tempera? So say when doing 1084 I fire it up to 1485 Put the blade in then the temp lowers. I wait 5-10 min and when temps are back up to 1485 soak ten min then quench. Am I giving the steel long enough to soak is what I'm asking. I keep seeing people say we don't leave them in our kilns long enough
 

KenH

Well-Known Member
Timing for soak starts AFTER oven is back up to target temp, then start the timer for soak time. Soak time depends on the steel alloy and how thick the blade is.
 

Kevin R. Cashen

Super Moderator
Set the oven then give it a good, long, time to regulate at your set temp. Then introduce the blades, wait for the rebound. On 10XX, using correct austenitizing temps, all you need to do is insure the blades have reached temp., as full solution can be achieved as low as 1375°F, and quench. ANYTHING with any alloying, beyond C and Mn, hold for 10 minutes, and then quench.
 
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billyO

Well-Known Member
Am I giving the steel long enough to soak is what I'm asking.
It's my understanding that simple steels (10XX) don't need to soak, so quenching as soon as the blade reaches your target temp is what you should be shooting for. How long it takes your oven to rebound is what you need to find out. This will depend primarily on how long you keep the door open to insert the blades, and how thick the blades are.
 

Andre Grobler

Well-Known Member
i find that my narrow long oven rebounds very fast when my blade doesn't quite reach the TC, but takes quite a few minutes if the knives touch the TC just about... so if i am doing shorter blades that are a little bit away from the TC i wait for a bit longer after rebound. if it touches, i start soak when rebound reaches set temp.
 

Jonnymichigan

Active Member
Set the oven then give it a good, long, time to regulate at your set temp. Then introduce the blades, wait for the rebound. On 10XX, using correct austenitizing temps, all you need to do is insure the blades have reached temp., as full solution can be achieved as low as 1375°F, and quench. ANYTHING with any alloying, beyond C and Mn, hold for 10 minutes, and then quench.
I normally let it hit target temp then wait 45 min after before introducing blades. Thanks Kevin
 

Jonnymichigan

Active Member
I normally let it hit target temp then wait 45 min after before introducing blades. Thanks Kevin
Set the oven then give it a good, long, time to regulate at your set temp. Then introduce the blades, wait for the rebound. On 10XX, using correct austenitizing temps, all you need to do is insure the blades have reached temp., as full solution can be achieved as low as 1375°F, and quench. ANYTHING with any alloying, beyond C and Mn, hold for 10 minutes, and then quench.
You think ten minutes is too long to soak 1084? I may have to get your 1084 video now too. I loved your grinding video. I learned a lot and use stuff I learned today
 

Drew Riley

Well-Known Member
Anytime I warm my oven up, I let it soak for at least for 30 to 45 minutes before putting any steel into it. From that point, I try to limit open door time, but it shouldn't take more than a minute or two for the heat to recover and stabilize, IMO. Full disclosure, I have roughly a 6x6x24ish chamber with a 3000W, 220V element. I suppose a larger chamber and/or smaller wattage oven might take a little bit longer to recover if the door is open for very long. If I have two or three blades soaking at once, and I take one out, I try to close the door right away. Usually by the time I quench, check for straight, wipe the oil off and take it over to the temper oven, the next blade is already back up to temp and ready to quench. I rarely soak more than 2 or 3 at time, just to limit the additional ups and downs with the door opening.

One thing you might do to help increase your oven efficiency and recovery time is to coat the inside with some ITC 100 or similar.
 

Andre Grobler

Well-Known Member
Anytime I warm my oven up, I let it soak for at least for 30 to 45 minutes before putting any steel into it. From that point, I try to limit open door time, but it shouldn't take more than a minute or two for the heat to recover and stabilize, IMO. Full disclosure, I have roughly a 6x6x24ish chamber with a 3000W, 220V element. I suppose a larger chamber and/or smaller wattage oven might take a little bit longer to recover if the door is open for very long. If I have two or three blades soaking at once, and I take one out, I try to close the door right away. Usually by the time I quench, check for straight, wipe the oil off and take it over to the temper oven, the next blade is already back up to temp and ready to quench. I rarely soak more than 2 or 3 at time, just to limit the additional ups and downs with the door opening.

One thing you might do to help increase your oven efficiency and recovery time is to coat the inside with some ITC 100 or similar.
My oven size is similar, but i gippo the system by letting my blade - especially huge thick competition choppers, or large thicker kitchen knives, touch the thermocouple, so i am monitoring the blade temp to a degree, it will not be just the blade, but it is sort of an average...
 

EdCaffreyMS

"The Montana Bladesmith"
I'm in the group who allows the oven to reach temp, and cycle...usually for 30-45mins, before placing the blade(s) in the oven. That being said, typically, the only time I use an oven for austinitizing heats is with stainless steels. With simple carbon steels (10XX), I don't soak.
Personally, my preferred method of heating is my salt tank, as it eliminates problems presented when using an oven... specifically scale, and evenness of heating.

What must be realize/understood, is that there are wide variety of variables that exist from shop to shop. That's the main reason there is no "one size fits all" method of heat treating. The trick is....to learn the major variables that exist in your own shop, and learn how to minimize or eliminate them.
 
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