Heat Treatment Processes That Require Controlled Atmospheres

Heat Treatment Processes That Require Controlled Atmospheres
There are several different heat treatment processes that may require a controlled atmosphere in order to be successful. Those requiring either an inert atmosphere or a hydrogen atmosphere include the following:

Annealing: used to soften a metal or change its microstructure
Bright annealing: performed in an inert atmosphere of nitrogen, hydrogen, or argon to limit oxidation; pure hydrogen is usually the preferred atmosphere
Brazing: when done on copper and silver, an atmosphere of pure hydrogen or, in some cases, dissociated ammonia
Carburizing: adds carbon to the surface of steel to increase its hardenability and typically uses an endothermic atmosphere
Carbonitriding: the diffusion of carbon and nitrogen atoms into the surface of a metal to increase hardness; nitrogen is usually added to the endothermic atmosphere
Nitriding: heating metal in the presence of nitrogen (usually in the form of ammonia) to increase both corrosion resistance and hardness
Neutral hardening: used to prevent oxidation and decarburization in tool steels by using an inert or protective atmosphere such as nitrogen or argon
Sintering: depending on the metallic compounds being sintered, uses either an inert/protective atmosphere or a hydrogen atmosphere
Tempering: used to increase grain size, ductility, and toughness of previously heat-treated metals
Hot isostatic pressing: similar to sintering, but performed at much higher pressures
These processes can involve a variety of metals and be used to prepare parts for many different industries, including aviation, tooling, healthcare, energy, automotive, military, oil and gas, electronics, and the semiconductor industry.