1080/84 Heat Treat in Kiln Question

[Dennis Paish]

Greetings,
What is the 'ideal' process and why;
1) Load the kiln (cold) with blades and start the HT cycle.
2) Load the blades once kiln is at desired temperature and then start the HT cycle?

Somewhere I read a post on this subject, but failed to find it again.

Best regards,

Dennis Paish

 

[samuraistuart]

Heat the kiln up, then place blade in. Faster ramp to heat keeps grain small (so I've heard). Some steels, like A2, have a slow ramp recommendation. Also, a big concern is over shooting your target temp. When your kiln reaches the target temp, often it might overshoot it, due to the rapid ramp. So best to have the kiln equalized at target temp, then place blade in. Once the readout has re-bounded back to target temp (it will drop a bit due to the cold mass of the blade), begin your soak timer. Actually.....with 1080 and 1084 there should be no soak needed. I do 5 minutes with Aldo's Vanadium 1084.

I go even a bit further. I wait 15 or 20 minutes after my kiln reaches target temp. Just in case it did overshoot. My kiln ramps so slowly (110v), it doesn't over shoot by much at all, but I wait just to be safe.

 

[Dennis Paish]

Greetings,
Do you set your kiln for 1500 or 1525?

Thanks,

DP

 

[samuraistuart]

Dennis, for 1084, 1500°F, 5 minute soak, just for thorough equalizing, more than any real "soak". I put the blade in and start the 5 minute timer without waiting for rebound, which usually only takes a minute anyway in my kiln.

 

[Stacy E. Apelt - Bladesmith]

Stuart has the info. To sum it up:

For 1084:
Pre-heat kiln to 1500F and let stabilize
Place blade in kiln and let rebound to 1500F
Let soak for 5 minutes
Remove and quench in fast oil *
Let cool in oil for about 30 seconds, and then air cool to room temperature
Temper twice at 400-450F for one hour each temper. Cool in water between tempers and after. *

*Immediately after the quench, count to five. At this point the blade can be quickly straightened with gloved hands between 900F and 400F. If it stiffens, stop straightening and let cool. Any further straightening can be done at 400-450F during the second temper.