Investment castings are heat treated in batch or continuous atmosphere furnaces.  Protective atmospheres are beneficial for maintaining the surface quality of the smaller precision cast parts.  Ferrous heat treating applications typically include oil quench hardening, normalizing, annealing, and carbon restoration.   

Atmosphere heat treatments for stainless steel castings vary by material composition.  400 series stainless steel castings are hardened in oil quench atmosphere batch furnaces and are also bright hardened in hydrogen and vacuum furnaces.  300 series stainless steel castings are solution annealed in water quench atmosphere batch furnaces.  Precipitation hardening stainless steels are age hardened in atmosphere and non-atmosphere batch furnaces and in vacuum furnaces.

Non-atmosphere heat treatments include tempering, stress relief, and sub-critical annealing.  Finishing treatments include glass bead and steel shot blast.