Abstract
The reaction of dissolved oxygen with silicon in liquid iron was studied by using silica, alumina and magnesia crucibles to know the effect of the contamination of reaction product with refractory materials on the deoxidation constant. The concentration product [%Si]·[%O] 2 in liquid iron held in silica crucibles is expressed by the following equation and agrees well with previous studies:
log [%Si]·[%O] 2=24600/T+8.40.(1)
ΔG°=113000-38.4T.(1′)
The deoxidation constant with silicon was 0.5-0.6×10-5 in alumina crucibles and 0.13-0.14×10-5 in magnesia crucibles at 1600°.
Silicon is one of the important elements for the deoxidation in 18-8 stainless-steelmaking practice.
The detailed studies of deoxidation with silicon have been carried out in iron-nickel, iron-chromium and iron-nickel-chromium systems at the temperature of 1550°, 1600° and 1650°. Chromium increases the deoxidation constant while nickel decreases it. The results obtained are represented by the following two equations empirically:
(3)
From these results the following parameters were given:(5)
The deoxidation constant with silicon in 18-8 stainless steel was fairly good consistent with the value calculated from the summation of activity coefficients of each element dissolved in the liquid alloys.
