Scale after heat treat - O1 - 3/32"

[Rick Marchand]

If you have a programmable kiln, you can ramp up to it slowly... if you only have an infinite dial, I would be careful, the infrared/radiant heat from the element could overheat the blade before it evens out. By how much? I don't know.... but I have overtempered many times using a conventional oven, for this same reason.

I don't know if that sandy clay will have an increased insulating effect in the quench. Mine is really smooth and looks spray paint thin.

 

[JW Knives]

Okay, so how does this sound. I have access to an oven tomorrow morning so I really want to get this right.

I will work on evening out the clay coat, Im thinking its still thin enough to allow the steel to hat fully and evenly
Also I will put the blades in the oven cold and ramp it up slowly, allow for a 10-15 min soak and then quench

 

[Rick Marchand]

That sounds about right to me. (LRB corrected me, below) If you have access to a Rockwell tester, you can be sure that hardness was not affected.

 

[LRB]

one more question on the topic of oven treating O1, do you bring the blades up to heat along with the oven or do you preheat the oven and then put the blades in.

Something tells me you should put the blades in first and then set it to 1475 and go but again, I've read both...

No. You first let it ramp up to around 1250° for a 30 minute, to 1 hour soak for stress relief and pre-heat, then take it up to 1475° for at least a 15 to 20 minute soak before quench. I do a one hour pre-heat soak, then a 20 minute soak at 1475°, then quench in AAA.

 

[Rick Marchand]

Oops... yeah... LRB has it right. Its been a while since I had to think about O1. The pre-soak is recommended.

 

[AVigil]

Soak times for 01 is per inch thickness correct?

 

[LRB]

Not really. Considering the thickness of a blade, you may come up with a just a few minutes mathematically using that approach, and that will not get it done. It takes more than a few minutes to get a good solution with 01. The carbon goes into solution quickly, but the alloys do not. 01 can soak for hours at 1475° with no ill effect, so the point is almost moot. If one is in a hurry, they can use 1080/84 instead.