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Case-Hardened Steel

January 3rd, 2019

Case-hardened steel means creating a thin layer of a harder alloy on a metal surface by infusing elements onto it. The harder alloy on the outer surface is called the case, while the inner structure is called the core. Speciality Steel Treating offers several different methods of case hardening your steel.

Properties of Case-Hardened Steel

Case hardened steel properties include a core that is tough surrounded by a case that is hard. This gives the case hardened metal components extra durability as the core, or case depth, retains the ability to absorb shock while the hard outer case provides extra strength. Steel that is case hardened is equipped to resist the following:

• Abrasion
• Corrosion
• Wear

By contrast, a component that is not case hardened may develop cracks below the surface that cause pitting and flaking when they finally reach it.

Difference Between Case Hardening and Surface Hardening

Surface hardening involves keeping the core below its austenitizing temperature while heating the surface and then immediately quenching it (i.e., plunging it into a cold liquid) after that temperature is reached. This causes the core of the metal to remain soft while the surface hardens.

How To Case Harden Steel

Because case hardening involves adding an element to the metal, the different case hardening processes are named according to the element added. These elements include the following:

• Ammonia or other nitrogen-rich gas (nitriding)
• Nitrogen and carbon (cyaniding)
• Carbon (carburizing)

Case hardening steel involves infusing elements onto the heated metal surface and then quenching. The case hardening method used depends in part on the carbon content of the metal. 

Learn More About Case Hardening Steel

Large or small, simple or complex, case hardening has benefits for many steel components or tools. For more details, or to request an estimate, call Specialty Steel Treating at 586-293-5355.