S35vn heat treat question


Well-Known Member
Preheat: Heat to 1550-1600�F (845-870�C) Equalize.
Austenitize: 1900-2000�F (1035-1095�C), hold time at temperature
15-30 minutes.

My question is once you have preheated to 1550-1600 and soaked to equalize do you let it cool to 0 or immediately bring your temp up to 1900-2000?
No, that is a preheat so you should not cool it, you should ramp from there to Austenitizing temp.. In my testing, I've found that a preheat sequence isn't necessary. The preheats are more for thicker material like dies, shafts, etc.. Anything 1/4" or less doesn't really need a preheat IMO.
I go directly to the Austenitizing temp. and start my soak time when the furnace springs back to the low end of the Austenitizing range. For example, when doing S35VN, I equalize the furnace at 1975 and let it set there for about 10 minutes. Then I add the foil wrapped blade/blades and start my 30 minute soak when the furnace gets back to 1900. For high temp. steels, its better to undersoak than oversoak. Again these soak times are designed for thick pieces and it just doesn't take that long for a blade sized piece to reach the proper temp. and get everything into solution.
Good luck and let us know how it turns out.

Stacy Apelt

Active Member
I know this thread is a year old, but here is my CPM-S35VN recipe:

Program HT oven:
STEP 1 = RAMP to 1600F, hold for 30 minutes. This allows the oven to heat up and stabilize. It also allows me to do other stuff instead of waiting and watching the readout.
STEP 2 = RAMP to 1950F at 9999, hold for 10 minutes.

When it is at 1600F and stable, I put in foil packet with blade. I do not soak at 1600F, but immediately proceed to the next step.

I hit "advance to next step" and the oven climbs to 1950 for a 10 minute soak.

I pull the packet after the soak and quench packet between thick aluminum plates. Let cool for one minute.

Remove blade from packet. Set back in press plats for five more minutes. Remove and allow to cool to ambient for five minutes.

Place blade into LN or a dry ice slurry. LN for six hours, DI for 10 minutes.

Temper twice at 375-400F ( depending on use).

I now have Peter's do most of my S35VN. I believe Brad uses a similar regime.