Study of deoxidation processes

Deoxidation of liquid Fe-Ni and Fe-Ni-Cr alloys with manganese, vanadium, silicon, titanium and aluminium is experimentally investigated. Deoxidizing effect of chromium increases with increasing nickel content in iron, especially when nickel content exceeds 40 %. Deoxidizing ability of the studied elements is greater in Fe - 10 % Ni - 20 % Cr than in Fe - 40 % Ni - 15 % Cr alloy. The issues of deoxidation of melts with carbon in vacuum and in the neutral atmosphere are also discussed. It is shown experimentally that the absence of CO in the atmosphere does not significantly increase the deoxidizing ability of carbon. It is concluded that the chemical vacuum (zero partial pressure of CO) is not equivalent to physical vacuum (zero total pressure). A non-stirring gas layer exists above the metal melt, and the content of CO in this layer may determine the equilibrium concentration of oxygen at given concentration of carbon. Thus melting of metal in argon atmosphere at pressures of 10 5-10 4 Pa is not recommended for substantial decrease of oxygen content because deoxidizing ability of carbon increases; it can only be regarded as melting in a protective atmosphere preventing the melt from oxidation.