For matrices, the most common is the use of tool steel 1.2379. It is normally hardened to 60 to 62 HRC, where the high hardness and the too low tenacity become a problem and breaks occur often. That is especially the case with punching tools which are intended for long series production.
Hardox 600 and Hardox Extreme can be used as steel for punching tools, compensating for their high hardness with high toughness. Hardox sheets are pre-cured, making their production more complex. Difficulties can be avoided by first cutting the parts with hydrogen and then finishing them on the CNC machine.