ステンレス鋼浴におけるシリコンの脱酸能に関する研究

Abstract

Silicon is a prime deoxidizing element for stainless steel. It can be considered that the deoxidizing ability of silicon may be increased by reducing Asio2, under the basic slag. This effect, however, has not been understood clearly.Standing on this viewpoints, the study has been made of the SiOequilibrium for 18Cr-8Ni melt, and also of the effect of crucible materials and that of slag composition on the deoxidation power of silicon.The results are summarized as follows:(1) The experimental equations for Si-O deoxidation equilibrium for 18Cr-8Ni stainless melt are given as follows:(1)(2)The value of log Ksi at 1600°C accords well with that of the equation for Fe-Si-O system recommended by GAKUSHIN (Japan Society for the Promotion of Science, 19th Committee).(2) As to the effect of crucible materials on the deoxidation power of silicon, it is increased by the use of the CaO and CaO-SiO2 crucible, and the effect of Al2O3 crucible is considerablly small. The effect of MgO and ZrO2 crucibles is larger than that of Al2O3crucible but smaller than that of CaO crucible.(3) The deoxidation equilibrium of silicon under the CaO-SiO2-Al2O3 (sat.) slag has been measured at 1600°C, and the relation between the (%CaO)/(%SiO2) and aSiO2 has been determined. The result indicates that the oxygen value by silicon deoxidation is greatly influenced by the basicity of co-existing slag and that the observed values of aSiO2 are larger than the ones estimated from the slag composition.(4) From the above mentioned results, it can be concluded that the deoxidation power of silicon in the actual stainless steel melt is increased by using the basic slag. However, it seems to be difficult to attain the equilibrium oxygen value that accords with the value of aSlO2 expected from the slag composition.