| Abstract: | The present paper is the first part of a study on the improvement of the quality of ball-bearing steel made in basic electric furnace. The effect of deoxidation and casting practice onnon-metallic inclusions in steel during the steel-making process was studied. It was found that the non-metallic inclusions in ball-bearing steel could be markedly reducedwith the adoption of the following practice: On slagging off before the reducing period, silico-manganese was added for preliminary deoxidation; addition of crushed calcium carbide was thenmade to speed up the formation of carbide slag, which should be kept not less than 40 minutes;after this, ferro-silicon powders or crushed calcium carbide were added for slag deoxidation; slagmust be white before tapping; it is advisable to tap the slag first and then the liquid steel torender them thoroughly mixed in the ladle to facilitate further elimination of non-metallic in-clusions in steel; final addition was carried out by adding not less than 1/2 kilogram of aluminiumper ton of steel. Good-quality ladle linning and runners should be tar-soaked in order to decrease the amountof exogenous inclusions. It was noticed that titanium nitride inclusions in the steel were due tothe presence of titanium in ferro-alloys, the making of high-quality ball-bearing steel calls forthe use of titanium-free ferro-alloys. |
