This specification establishes the requirements and procedures for heat treating parts in a vacuum/partial pressure. This process has been used typically for the heat treatment of carbon and alloy steels, tool steels, corrosion-resistant steels, precipitation -hardening steels, super alloys, titanium, and other nonferrous alloys, but usage is not limited to such applications. Heat treatment as used in this specification includes solution treatment, homogenizing, austenitizing, annealing, normalizing, hardening, tempering, aging, and stress relieving. This specification does not cover processes such as melting, brazing, diffusion bonding, coating, carburizing, or nitriding. The objective of this process is to produce heat treated parts which are free from surface contamination and alloy depletion. Such parts may not necessarily have a bright surface.