S7 is a popular Shock Resistant cold work die steel that is also very commonly used as high quality Mold Steel. It offers very high shock resistance, good wear resistance, good machinability, and good stability. S7 is readily available in Plate, Block, Round Bar, Groundstock, and Drill Rod forms. The optimal hardness range is 52-58 HRC.
For more detailed information download the tech bulletin PDF below:
AISI S-7 Air Hardening Shock Steel