A8

A8 is a medium carbon, air-hardening tool steel that is characterized by a combination of very good toughness, intermediate wear resistance, and excellent dimensional stability in heat treatment. Has been used for punches that operate in the 55 to 60 Rockwell C hardness range. For hot work toolling applications, A8 tool steel provides better resistance to erosion, wear and wash-out then the typical chromium-molybdenum hot work steels such as H11 and H13. This alloy is not recommended for hot applications where thermal fatigue (heat checking) is the primary failure mode.