| 摘要 |
PURPOSE:To control effectively the dendritic segregation and the adding one and more kinds of Be, Cr, Nb, Sn, Ti and V in the specified quantity into a molten steel in the casting of middle or low carbon steel. CONSTITUTION:In the casting of carbon steel contg. <=0.53wt% C, one and more kinds of Be, Cr, Nb, Sn, Ti and V are added respectively by <=2% and if necessary, <=2% Mo is added. The delta phase (=alpha phase) region is extended by the addition of alpha stabilizing element. As the result wherein the delta phase region in the dendritic crystalline part is increased, the region that the delta phase and the alpha phase coexist is extended and the reaction rate of peritectic or the Ar4 transformation degree is increased. Therefore the separation of alpha stabilizing element (e.g. P) and gamma stabilizing element (e.g. Mn) which is caused by the difference of the solubility into the delta phase and the gamma phase is accelerated and the double segregation in the dendrite 21 is decreased. |
