Hardening includes both through hardening and case hardening.
- Processed in an endothermic atmosphere or vacuum
- It ensures the material is the same hardness at the core as it is on the surface, based on hardenability
- Common through hardened material is 4140 and 420SS
- Traditionally performed in an endothermic atmosphere
- Ensures the material is harder on the surface than at its core
- Creates a wear resistant surface while maintaining a tough, ductile core
- Includes carbonitriding and carburizing
- Typical case hardened materials include 8620, 1018 and 12L14 steels
- Nitriding is also a case hardening process, and is performed on various stainless steels, 4140 and ductile iron.