Metal stampings, because of the required high quality surface condition, are heat treated in nitrogen protective atmospheres, hydrogen reducing atmospheres, and vacuum.  Stampings may be heat treated in either batch or continuous furnaces depending on part geometry and dimensional tolerances.

Medium carbon and alloy stampings are typically hardened in oil quench batch and continuous furnaces or in austemper (molten salt quench) furnaces.  The oil quench process produces a martensitic structure whereas the austemper process produces a bainitic structure.  The austemper process is typically used for dimensional characteristics or for certain mechanical properties.  Low carbon steel stampings are often carbonitrided to produce a high hardness wear resistant surface on a ductile, impact resistant core.  The depth of case hardening on the surface is typically 0.005” to 0.040” although deeper case depths are possible for larger stampings with increased furnace time and temperature.

Carbon steel and 300 series stainless steel stampings are bright annealed in hydrogen protective atmospheres and in vacuum.  Hardenable 400 series stainless steel stampings are bright hardened in the same hydrogen atmosphere and vacuum furnaces.  All of these carbon and stainless steel stampings may be furnace brazed in the same hydrogen atmosphere and vacuum furnaces.

The most common heat treatment of non-ferrous stampings is the solution anneal and age harden of aluminum stampings.  The heat treatment is typically performed in batch and continuous non-atmosphere furnaces.  Aluminum heat treatment also requires strict temperature control, especially for military or aerospace applications.  Other non-ferrous materials may be bright annealed in atmosphere and vacuum furnaces.

If additional cleaning of the heat treated metal stamping is necessary, glass bead finish with light pressure is used to preserve the high quality metal surface.