What is Case Hardening?

Case hardening is a heat treatment process used to selectively harden the surface of a metal, usually low-carbon steel.  The goal is to create a part with the following qualities:

• Hard, wear-resistant surface: This outer layer offers superior resistance to scratches, abrasion, denting, and fatigue caused by repetitive stress.
• Tough, ductile core: The inner core maintains higher ductility and toughness, providing the part with the ability to absorb impacts and resist deformation without breaking.

Benefits of Case Hardening

• Enhanced Wear Resistance: The hardened surface dramatically improves resistance to abrasion, scratches, and indentation.
• Improved Fatigue Strength: Case hardening helps prevent cracks from forming and propagating under repetitive stress and loads, extending the part's lifespan.
• Maintains Core Toughness: Unlike through hardening, the core remains relatively soft, providing shock resistance and preventing catastrophic brittle fractures.
• Cost-Effective: It's often more cost-efficient to case harden a low-carbon, less expensive steel than to use a high-carbon steel for the entire component.

Machining Considerations

• Hardened outer surface will increase tool wear on O.D. Turning operations such as parting, grooving, facing.
• Recommend use of specialised turning inserts (e.g. CBN Tipped inserts)
• Suitable for griding operations (e.g. Cut-Off wheel, surface grinding flat features)
• Ductile core allows end drilling & tapping without the need for specialised tooling.

Published : 27-Feb-2024