Cooling ht oven

[Matt Rochester]

So, I am heat treating some Cpm154cm. I heat treat, plate quench, sub zero, and then temper. Problem is, it takes a long time for my oven to cool down to tempering temp. Can I wait(2-3 hours) for it to cool off, or do I need another oven? Also, I know there is probably not a simple answer but, if I hit my targeted RC is my heat treat a success? Can you get the correct hardness and still not have a sufficient heat treat.

Also, happy Father's Day to all the dads out there. It's an honor and a privlage to be called dad, we should never take that for granted!

 

[Stacy E. Apelt - Bladesmith]

Just leave it in the sub-zero bath until it cools. Once it is at the Mf, a delay of several hours won't matter.

Yes - If the HT went right, the results should indicate such. Hitting a high Rc at quench and the expected Rc after temper are how most folks determine a good HT.


In a poor HT, you may get a lesser amount of martensite. You can fudge the numbers to get a certain final result, but that isn't the same as doing it right.. An example of what I mean is some folks do a poor HT with 1095 and temper at 300F and get Rc 58. That should be a hardness of Rc63-64 if the HT was right. If it was done right, a temper of 450F would get Rc58. The two knives would have the same hardness, and would both get sharp....but the proper HT would probably have a longer lasting edge life.