Observations on oxygen melting of stainless steel

The paper discusses the efficiency and economy achieved in different stages of melting, oxidation reduction and refining in the reduction technology of stainless steel, on the basis of factory floor experience gained, observations made and data collected by the author in a number of leading alloy and stainless steel producing firms of the United Kingdom. Thermal and chemical factors in different stages of production of stainless steel have been explained on the basis of physico-chemical principles and thermodynamic considerations involved. The role of oxygen in stainless steel melting and the free energy of formation of different oxides have been detailed. The efficiency of oxidising period has been shown to depend mainly on the rate and pressure of oxygen during blowing and chromium-carbon temperature relationship of the bath. It has been observed that the efficiency of slag reduction reactions is mainly controlled by slag basicity and rate of approach to slag-metal equilibrium. It has also been found that furnace size, basicity of slag and silicon content of the bath have been profound influence on chromium recovery and economics of production. (Mr. R.K. Dubey, Senior Scientific Officer, National Metallurgical Laboratory, Jamshedpur)