Following the results of previous experiments, made by others interested in this field, on the deoxidation effect of high-temperature melting of cast iron, we carried out some fundamental experiments on the effects of Ca-Si inoculation using normal laboratory apparatus and processes. Using low P pig-iron in market or synthetic pig-p iron prepared from electrolytic iron and charcoal, we studied how the conditions of inoculation ; the constituents of raw materials, metal temperature for inoculation, quantity of the inoculant and time interval from inoculation to pouring, affect on the microstructures and the mechanical properties of so-treated pig iron. Some results obtained are as follows : (1) Ca-Si inoculation at least 0.3% is necessary for the improvement of microstructure, while 0.1% inoculant is satisfactory for decreasing chill depth. The effects of inoculation disappear in about 10 to 15 minutes after inoculation and this may be considered rather rapid. (2) The influence of Ti and Mn in raw materials on the effects of inoculation can not be neglected. (3) Superheating of melt and increasing of Mn content are effecteve for obtaining small-sized and uniformly distributed graphite features. (4) An Si increase and a slight S decrease were noted : however, a considerable increase in N
2 and a decrease in O
2 were observed. (5) The improvement of mechanical strength of pig iron by inoculation is obvious especially when Sc and P are low ; on this ground, the greater part of the charge metals should be steel scrap in actual melting operations.
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