packcarburisatie

Pack carburisation, or pack carburizing, is a traditional case-hardening heat treatment in which steel components are enclosed in a carbon-rich packing material and heated to temperatures that permit carbon diffusion into the surface. The result is a hard, wear-resistant outer layer (the case) with a tougher, more ductile core after appropriate quenching and tempering.

In practice, parts are placed in a sealed container with a carbonaceous pack, typically containing charcoal or powdered coal, sometimes mixed with a binder and small amounts of activators or salts to control carbon potential and reduce oxidation. The pack is heated to about 900 to 950°C (1650 to 1740°F) for several hours, during which carbon diffuses into the surface. Because the process occurs with limited gaseous activity, it minimizes oxidation and allows treatment of large or geometrically complex parts that may not suit gas-based methods. After diffusion, parts are removed from the pack, quenched to harden the surface, and then tempered to achieve desired toughness and reduce brittleness.

The carbon content in the surface layer can be higher than in the core, enabling a hardened case while maintaining a softer interior. Case depths vary with time and alloy composition and are typically in the range of 0.5 to a few millimeters for many applications. Pack carburising is commonly used for gears, shafts, cam followers, and other components requiring a wear-resistant surface.

Historically widespread, this method has declined in some regions with the rise of gas and vacuum carburizing, but it remains valuable for certain large parts, special alloys, or where precise control of carbon potential is difficult with gas-based processes. Safety concerns include handling hot packs and butane- or charcoal-related off-gases.