How does a vacuum prevent unwanted chemical reactions during metal processing?

In metal processing, vacuum technology prevents unwanted chemical reactions—specifically oxidation—by removing reactive gases from the environment surrounding the metal.12

At elevated temperatures, metals are highly susceptible to reacting with oxygen in the air. By utilizing a vacuum furnace, processors can perform heat treatments in an environment devoid of air, thereby preventing the formation of surface oxides.2

In steelmaking, vacuum treatment is used to manage dissolved gases and control chemical composition. By lowering the pressure, the system facilitates the removal of dissolved hydrogen and promotes the reaction between dissolved carbon and oxygen to form carbon monoxide, which is then extracted. This process is particularly critical in the production of high-alloy steels, such as stainless steel; for instance, a vacuum oxygen decarburizer (VOD) allows for the removal of carbon while preventing the overoxidation of valuable alloying elements like chromium. By manipulating the pressure-dependent equilibrium of these reactions, manufacturers can achieve precise metallurgical results that would be impossible in an atmospheric environment.1