Microprobe Study of Nonmetallic Inclusions in Rail Metal Cast under Exothermal Slag Impurities.

A study was made of the nonmetallic-impurity composition in Bessemer rail metal smelted in 22-ton converters, deoxidized by silicomanganese and aluminum in the ladle, and cast in 4. 3-ton ingots from above through a layer of an exothermal slag mixture. It is found that a very small concentration of impurities capable of becoming bonded to the slag mixture indicates that the metal is not being contaminated by slag components. The total concentration of nonmetallic impurities in samples of metal cast through slag is lower than in samples cast by the ordinary method.