Degassing and deoxidizing of the metal is directed at production of especially low content of carbon and impurities in the finished steel.
In the reaction of the metal deoxidizing by carbon (in contrast to all other deoxidizers-elements) form gaseous deoxidizing products, that's why reduction of the pressure increases deoxidizing capacity of carb on, whereby significant influence exerts temperature.
To prevent poppling in the ladle during tapping because of high level of the metal oxidation, preliminary deoxidizing of the latter by aluminium was performed.
It was experimentally established that using method of vacuum degassing of the metal it is possible to achieve required low content of carbon (less than 0.01 %) both in degassing of the metal with preliminary deoxidizing by aluminium and without introduction of the latter.
Silicon consumption over periods of melting, % Reduction Diffusion deoxidizing
of final slag 1 100 -- 2 80 20 3 80 20 Melt No.
Constant of ferronickel deoxidizing by silicon has the following form:
For the case of iron deoxidizing by silicon dependence of lg [K'.sub.Si] upon temperature is as follows:
Equilibrium content of oxygen in iron (approximately the same is in ferronickel) depends upon weight share of silicon and temperature; the lower is temperature the higher is deoxidizing capacity of silicon because of exothermic nature of reactions of interaction of silicon with oxygen.
Deoxidizing of ferronickel by aluminum may be presented by the reaction:
The addition of deoxidizing
or reactive elements (Al, Ti, Si, C, Mg, etc.) will reduce the soluble [O.sub.2] content in iron.
elements and compounds were tested using closely controlled heats of AOD refined 17-4 stainless steel, with .04% addition of a reactive element.