Prediction and Control of Segregations in CrMoV Steel Ingot for Monoblock Hlp Rotor Forgings Using Experimental Results Obtained From 8 Ton Sand Mold Ingots

摘要

Remarkable segregation was observed in the modified super clean CrMoV steel forgings for electric power generation applications. Therefore, to make the mechanism clear, effect of such elements as Mn, Ni, Cr and Mo on segregation was studied, using 8 ton sand mold ingots, the solidification time of which corresponds to that of 100 ton ingot. As a result, we found that factors controlling the segregation are delta-solidification ratio, mean partition coefficient, density difference of molten steels between bulk and segregated liquid at the solidification front and so on. These factors can be calculated from chemical composition of steels.