time to bring blade up to temp?

[Radar]

Okay, stupid question time.

So, is there a way to estimate how long it will take a blade at room temperature to equalize at the set temp in the heat treat oven?

Basically, I'm looking for a guideline as to when to start the clock on the soak time.

Thanks All.

[racjarrett88]

i put it in and let it warm as the oven does

[Ray Rogers]

You either put it in the oven while the oven is cold as Austin suggested or put it in after the oven has reached the desired temp. Either way, the soak time starts when the oven is at the right temp and the blade is in there. Obviously, the soak time could be a little different under these two conditions so testing the resulting blade would give you guidance. Or, simply set the soak time long enough to be sure, say 10 minutes, should work fine either way for 1084 for example ...

[Radar]

I'll be working with 1095 and understand that the soak times are pretty short, basically just enough to heat it through. Is there any harm in creeping up on the austinizing temperature (1475?F) slowly? I think the fastest my oven will heat is 70?F/minute, and it's slower than that as the temperature increases.

[Ray Rogers]

The longer it takes to reach temp the longer the blade has to develop scale. You could just wait until the oven reaches temp and then put the blade in. After the oven recovers from having the door opened start your soak time count....

[Radar]

Thanks, that's what I was looking for. These particular blades are only 1/16" thick, so it shouldn't take long for them to reach temp. I just wasn't sure how many minutes I should allow for temp ramp.

-Radar

[Gary Mulkey]

Ray is right on in saying to preheat the oven and start counting the soak time when the oven returns to temp after opening the door. [Remember to stop & restart the program after placing the blade in the oven so that the oven immediately reheats to temp.] I'm assuming that you are speaking about H/T temps and if so, when you slowly bring the blade up to temp you risk grain growth so it is preferable to heat it quickly. If you are talking tempering temps then the ramp time doesn't matter but by putting a blade into a cold oven you risk overheating it as the oven ramps up to temp since there may be hot spots.

Gary

[Radar]

You are correct, austenizing temps, not tempering temps. For the short times we're talking with 1095, I''ll probably just keep an eye on the clock rather than reset the programmed time on the oven. I've also got some O1 blades of the same profile. It'll be interesting to see the hardness I get from both, based on theoretical maximum. The oil I have is the 11 second oil from McMaster. Probably better suited to the O1 than the 1095, but we'll see. With a little luck and vigorous agitation, maybe I can get past the pearlite nose on the 1095. My blades are only 1/16" thick, so at least I have that going for me.

As for hot spots, one thing I was thinking of doing is shielding the blade (not wrapping it) with SS foil so the radiant heat from the elements don't asymmetrically heat the blade. I'm not sure how necessary that is, but it seems that it can't hurt.

-Radar

[Gary Mulkey]

Originally Posted by Radar

You are correct, austenizing temps, not tempering temps. For the short times we're talking with 1095, I''ll probably just keep an eye on the clock rather than reset the programmed time on the oven.
-Radar

What happens with my Evenheat is that the temperature naturally drops when I open the door but the oven still thinks that it is at temp and doesn't re-engage the elements to compensate for the lost heat unless I reprogram it by stopping & restarting.

Gary

[Radar]

I'll watch for that. My oven is a Ney Vulcan, I'm new to this so I haven't used it enough to become that familiar with it.

[mete]

Instead of trying to shield the blade with foil use a piece of pipe .

[Doug Lester]

I have a small stackable kiln that I've used for other projects. When it gets warm enough outside to start forging again I think that I'm going to set it up to heat treat in until I can save up enough to purchase a heat treating oven. One of the things that I remember from using it the last time is that it is bright enough to make my eyes ache. It would be a good idea to have IR resistant glasses on to work with it. I got a pair from a pottery equipment supply house on Ebay for less than $25, minus shipping.

Also don't open the forge without turning it off or disconnecting the power. I'd hate to make contact to a coil with the blade while the power's on. Might short out my shorts.

Doug

[Radar]

My oven has a safety disconnect on the coils when the door's open. Even so, I'm going to resist the urge to put my tongue on the coil for fear of getting shocked.

[modes]

This requires a little detective work in the form of tapping the wall with a hammer