My first CPMS35VN heat treat

John Barker

SUPERModerator & KNIFE MAKER
Well, I managed to heat treat a batch of four CPM S35VN blades this last weekend. Here's what I did.

Wrapped in SS foil. No paper or wood in the pouch.

Put in my evenheat oven and turned it on.

Let equalize at 1575F for 10 minutes.

Ramped up to 1950 and held for 20 minutes.

At that point I started taking the blades out one at a time and plate quenched them for 2 minutes each and let them finish cooling in front of a fan on high. The longest time a blade was soaking was for 30 min.

After cooling to room temp, I put in liquid Nitrogen for 10 hrs.

Then I tempered twice for 2 hrs at 500 deg.

All my blades Rockwell tested at 60.

-John
 
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Ron, I can't speak for John, but I get my LN at Airgas or Tri-Gas. As for storage, I picked up a liquid nitrogen dewar from a guy on Bladeforums a while back. It is surplus from some sort of genetics/biochem company. Check ebay for used dewars. If possible, get a guarantee that it is in good working condition as they can be somewhat delicate, and if the vacuum is breached, it's no good.

--nathan
 
I got my nitrogen at a local welding supply shop. They happen to have it on hand. I have a 20 liter Dewar that I bought a few years ago on Ebay. It was brand new. It cost me $30 to fill my dewar and it lasts for about 4 months.
-John
 
Thanks guys. I have several Airgas stores in the area & I can also call some local welding supply shops.
 
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