Abstract
By statistical research on the effect of melting procedure on the ductility of cast steel, it was verified that sulphur has an unfavourable influence on the toughness of cast steel, especially elongation, reduction of area and impact value. In order to clarify the influence of sulphur on the mechanical properties of cast steel, several SC42 specimens with varied sulphur content from 0.01% to 0.06% using pure iron as base materials were melted and cast.
Mechanical properties of cast steel deteriorated with increase of sulphur content. Elongated inclusions with forging in cast steel increased by sulphur addition. Meshy inclusions which appeared in austenite grain boundaries of high sulphur specimen were principally (Fe, Mn)S inclusions. It is considered that these turned into elongated inclusion by forging. There were many spherical inclusions in the dimples of the fractured surface of high sulphur content specimen and they were (Fe, Mn)S inclusions. Because of the above, the increase in the (Fe, Mn)S inclusions in the austenite grain boundaries resulted in the decline of mechanical properties of cast steel.
