This should be easy for TKS to track. S90V (420V) has an autenitizing temp and tempering temps which would mean it is not going to be included in a run with most other steels. There just aren't many steels that we use that harden at 2100-2150F. Also, assuming it was hardened correctly, the tempering would have had to be well over 1000F to get HRC that low. Surely TKS would notice if they went way over or under these temps, unless it got tossed in with stuff like S30V, ATS34, etc??
While I understand the principle of using sample tabs for monitoring a run, I personally think that a well run operation doing custom knife blades should check every single blade to make sure there weren't any mistakes.
I agree you should call them and discuss this, Bryan, if for no other reason than to help another maker avoid the same problem.
Don, I forget who (of course!), but someone else was doing the dot-triangle a long time ago, right next to their name on the ricasso....
It's a cool idea, IMHO.
All of the HT schedules for Crucible steels are available at
www.crucibleservice.com
they have slipped a bit on some of the CPM's, though, in that they don't include tempering curves or charts, just a broad range. That's sort of funky on a secondary hardening steel.