Diffusion hardening

Schematic cutaway view of a diffusion hardened metal gear

Diffusion hardening is a process used in manufacturing that increases the hardness of steels. In diffusion hardening, diffusion occurs between a steel with a low carbon content and a carbon-rich environment to increase the carbon content of the steel and ultimately harden the workpiece.[1][2] Diffusion only happens through a small thickness of a piece of steel (about 2.5 μm to 1.5 mm), so only the surface is hardened while the core maintains its original mechanical properties.[2] Heat treating may be performed on a diffusion hardened part to increase the hardness of the core as desired, but in most cases in which diffusion hardening is performed, it is desirable to have parts with a hard outer shell and a more ductile inside. Heat treating and quenching is a more efficient process if hardness is desired throughout the whole part. In the case of manufacturing parts subject to large amounts of wear, such as gears, the non-uniform properties acquired through diffusion hardening are desired. Through this process, gears obtain a hard wear-resistant outer shell but maintain their softer and more impact-resistant core.[2]

  1. ^ "Diffusion Treatment Hardening". eFunda: Engineering Processes. www.efunda.com/home.cfm. Retrieved 15 January 2013.
  2. ^ a b c Todd, Allen, Alting (1994). Fundamental Principles of Manufacturing Processes. Industrial Press Inc. ISBN 9780831130503.{{cite book}}: CS1 maint: multiple names: authors list (link)