Case Hardening - Applications

Applications

Parts that are subject to high pressures and sharp impacts are still commonly case hardened. Examples include firing pins and rifle bolt faces, or engine camshafts. In these cases, the surfaces requiring the hardness may be hardened selectively, leaving the bulk of the part in its original tough state.

Firearms were a common item case hardened in the past, as they required precision machining best done on low carbon alloys, yet needed the hardness and wear resistance of a higher carbon alloy. Many modern replicas of older firearms, particularly single action revolvers, are still made with case hardened frames, or with case coloring, which simulates the mottled pattern left by traditional charcoal and bone case hardening.

Another common application of case hardening is on screws, particularly self-drilling screws. In order for the screws to be able to drill, cut and tap into other materials like steel, the drill point and the forming threads must be harder than the material(s) that it is drilling into. However, if the whole screw is uniformly hard, it will become very brittle and it will break easily. This is overcome by ensuring that only the case is hardened and the core remains relatively soft. For screws and fasteners, case hardening is less complicated as it is achieved by heating and quenching in the form of heat treatment

For theft prevention, lock shackles and chains are often case hardened to resist cutting, whilst remaining less brittle inside to resist impacts. As case hardened components are difficult to machine, they are generally shaped before hardening.