From oven to quench

[Mark Behnke]

Hello, new here but my interest goes back along time, been forging as a hobbie and atempted a few knives in the past.

Recently set up my shop to make knives. I have ground a blade 5160, double edge dagger and put it in my converted wax burn-out kiln for heat treat.

When I open the door the tip of the blade cools to black almost immediatly. It's ground to about .030 which is probably too thin. Other than that are there any methods to get to quench faster or keep the blade from cooling so fast?

Thanks in advance
Mark

 

[KnifeMaker.ca]

Mark

I'm not an expert on 5160 - but I think the whole idea is to get it to cool fast. As long as you get the whole thing cooled "under the nose" you should be fine. I think the problem is parts cooling too slowly - not so much too quickly - (except of course rapid cool shock like water).

Looking forward to other responses.

Rob!

 

[Mark Behnke]

You're right Rob. I feel like a real idiot, maybe it's my age.

 

[Stacy E. Apelt - Bladesmith]

Part of that is a visual thing, and part is actual. One reason for the soak time on a blade is to assure that the entire blade, not just the edges, is at the austenitization temperature.

5160 has something like five seconds to cool down below 900F, so if the tip drops more quickly, that is good.

Make sure the soak time starts at the point the oven and blade come back to the desired temperature, not when you put it in. Burn out ovens have a large air volume, and take a good while to return to set temp. Adding a large thermal mass to the oven will increase heat up time, but will make for a better knife soak time. Put a large block of steel in the oven. Depending on the oven chamber size, a 12X6X3" block will work nicely, but a smaller block will still help a lot. The block will heat up to the set temp, and when you open the door to insert the knife, will not loose much heat. Upon closing the door ( after inserting the blade) the temperature will recover ( and be more even) faster. You will also have less temperature drop upon removing the blade for quench. This is the most practical way to use a burnout oven for multiple blades.
Stacy