About D2|High-carbon, high-chromium cold work tool steel (1.5% C, 12% Cr). Semi-stainless. The chromium gives it better corrosion resistance than
A2 or
O1, though it's not truly stainless. Excellent wear resistance at HRC 58-62. Air-hardens with minimal distortion. The go-to steel for high-volume stamping dies, slitting knives, and forming tools where edge life matters most. Machines in the annealed condition with carbide. After hardening, it's grinding, EDM, or hard machining with CBN. Also popular for knife blades. Compare to A2 (tougher, less wear-resistant) and
M2 (HSS, better hot hardness for cutting tools) and 440C stainless (true stainless, similar hardness but less wear-resistant).
