Reducing atmosphere

A reducing atmosphere is one whose constituent gases will remove oxygen from the metal oxides on the surface of the components during heat treatment.

The most common reducing gases used in heat treatment are hydrogen and carbon monoxide.

Hydrogen is converted to water by reaction with metal oxides. (M stands for any metal.)

MO + H2 → M + H2O

Carbon monoxide is converted to carbon dioxide by reaction with metal oxides.

MO + 2CO → M + 2CO2