After my second temper on all 8 blades, the hardness has increased around .5 to 1 point on every blade. None lost any hardness.
The answer is NO. You want 0 rest time. hand warm into ln2 AQ and after each temper cycle. Another note: Certain alloys do not benefit very much from cryogenic treatment such as D2. Most basic carbon steel and higher carbide (15-20%+) steels benefit the most.I’m a semi pro knife maker using mostly high performance steels such as CPMS35VN and CPM154 for fix blades and my flipper-folder design. I live in a fairly remote community in eastern Washington. Dry ice availability for cryo treating is an
hour each way. I try and get ready 3-4 knife blades at a time to cryo treat but often that doesn’t work. Question to the guys in the know. Can I say build my folding knives and at a latter date cryo treat them. Understand I would have already hardened the blades @ 1950 deg and tempered @ 2 two hour sessions @ 400deg. I assume I might be able to take the knife apart, cryo the blade and then re heat treat. Whats your thoughts? Can I do that?
Oh my thank you for pointing out how utterly terrible and many stress risers are in commercially produced folders that I have to chamfer with a dremel ffs.You could get it just above 60 with a little experimenting… and quenching a little faster will help, using aebl or something expensive like the pm steels, that respond well to heat treat at lower temps will allow that easily using high range tempers for a redunction in toughness, and more wear resistance would get you to that goal too… but seeing the stress risers in modern flippers and folder pivota would make me heaitate about that…