Formation of hot-top segregation in steel ingot and effect of steel compositions

Convection and composition variations in the liquid zone during solidification of H₂O-NH₄C1 solution, which has the same model of convection as that of steel ingot, are studied. It is shown that a weak convection region forms near the ingot top in the liquid zone at a certain stage of solidification and then develops downward gradually, and the negative segregation is detected in the weak convection region. This interesting phenomenon reveals the formation process of hot-top segregation in steel ingots. The parameter dp _L /df _L, an important factor affecting the formation of hot-top segregation, is established as a function of the steel composition. When dp L/df_L is decreased by changing the steel composition, hot-top segregation will be impeded.