On the Rates of Oxygen Absorption of Liquid Fe-Cr and Fe-Cr-Ni Alloys

Abstract

The rates of oxygen absorption of liquid Fe-18Cr, Fe-18Cr-8Ni and Fe-25Cr-20Ni alloys from O₂-Ar and CO₂-Ar gas mixtures have been measured. The initial rate of oxygen absorption is proportional to the partial pressure of oxygen or carbon dioxide, independently of alloy and gas mixture compositions. The results agree with those of liquid iron obtained in the stream of O₂-Ar gas mixtures. The oxygen absorption of those alloys is simulated by the same model applied to the oxygen absorption of liquid iron, when the partial pressure of oxygen or carbon dioxide is higher than 0.003 atm. Accordingly, it is probable that most of gaseous oxygen dissolve into liquid phase through the oxide free interface, although some of them are transfered by the dissolution of oxide formed at the gas-metal interface. Furthermore, the amount of oxygen accumulated at the interface as oxide phase should be larger than that in liquid iron under the same oxygen potential.
When the initial carbon concentration in melts is somewhat high, the oxygen absorption accompanying decarburization is significant even under the condition that the rate of decarburization is controlled by the mass transfer of oxidizing gas.