EFFECT OF SLAG PREPARED WITH DIFFERENT COOLING METHODS ON CLEANLINESS OF BEARING STEEL GCr15

Bearing steel required high cleanliness. During LF refining, the type of slag has obvious effect on its cleanliness. Two kinds of refining slags have been prepared with different cooling methods after pre-melting. Another slag was used by only mixing the raw materials.Then six heats steelmaking experiments were carried out in the MoSi2 electric resistance furnace to study their effect on the cleanliness of bearing steel GCr15. The results show that: The water-cooled slag is full of glass phase or microcrystal phase inside, and it has the lowest melting point, the shortest melting time, the fastest desulfurization velocity and the smallest average size of inclusions. Those effects of the air-cooled slag are better than the mixed-slag's. Under the same process, the inclusion numbers and area in the steel refined by the slag with CaO/Al2O3=1.65 are smaller than those of the slag with CaO/Al2O3=0.94.