高炭素Si-Mn脱酸鋼中の酸化物粒度分布測定法の確立

抄録

The measurement of the particle size distribution of oxides in high carbon Si-Mn killed steel was achieved by extraction of oxides and the measurement with laser diffraction particle size analyzer.
The extraction method of oxide in steel by using nitric acid could not be applied to the present case because nitric acid decomposed the SiO₂ formed in steel. On the other hand, bromine-methanol method was suitable for the extraction of these oxide. Otherwise, the dissolving reaction was disturbed because of high carbon content. Decarbonization of the samples in H₂H₂O atmosphere was found to be effective as a pretreatment of the bromine-methanol extraction in order to avoid the disturbance in the extraction procedure for high carbon content steel.
The bromine-methanol extracts the free carbon as well as the desired oxides. But the KMnO₄ treatment with citric acid could dissolve only free carbon, and the oxides could be separated.
It was found that the amount of oxides at the surface area of bloom was greater than that at central area of bloom in case of both fine particle size of the oxides and large particle size of the oxides.