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Glossary
Case Hardening
A heat treatment process that hardens the outer surface of a fastener to resist wear and abrasion while keeping the core softer and more ductile (flexible). This combination provides a hardened, wear-resistant exterior and a flexible core that helps absorb impacts and resist cracking or breaking under stress. This balance improves overall durability by combining hardness with some internal flexibility.
Article: Case Hardening Explained