Compatibility of D-2 tool steel and TiCN coatings

I understand that applying TiCN to hardened D-2 punches will draw back the hardness a few points. Is this true? If so are there any different processes or coatings that provide good wear resistance without drawing back the hardness of the punch?

Bill, D2 is generally tempered at 450F, which is below the temperature of MOST PVD processes. The Cathodic Arc subset of PVD processes can take place at that temperature or below, but remember that you may not get the adhesion you'd like and that CA type processes can leave small particulate on the coated surface, so you have to let your vendor know whether such would be acceptable.

Can you switch to M2 for your punches? That can certainly take the temperature of the PVD process.

I'd recommend you talk to your PVD processor, or to Richter Precision (who's done good work for us) if you haven't selected a vendor yet.