Influence of Rare Earth Metals on Non-Metallic Inclusions in Cast Alloy Steels

The chromium and silicon steels usually have defects leading to lower fatigue and toughness characteristics
and cracking in the use. A study of Cr27 & silicon Si3 steels has shown that they contain coarse aluminates and silicates which possess high elongation.
Two series of heats were prepared with 0.5 kg/t to
2 kg/t rare earth metals (RE ) study 'then influence on these defects, Experiments were carried out in induction furnace (160 W). The results showed that oxygen and sulphur contents in silicon steels reduced from 0.0021%
to 0.0028% and 0.001% respectively. The inclusion level was the lowest ( 0.0188 area %), when RE added into steel was 0.5 kg/t. The optimal residual RE content in chromium steel was 0.013%, and 92.68% inclusions had smaller size than 41tm. The samples (did not have inclusions of size over 10 um, The inclusions morphology was small-smooth globular of type Ib. The composition of inclusions corr- esponded to RE oxysulphides and complex oxysulphides.