Behaviors of Manganese-Sulfide in Aluminum-killed Steel Solidified Uni-directionally in Steady State—Dendrite Structure and Inclusions

Abstract

Morphology, size and distribution of II-type manganese-sulfide are investigated taking steel-dendrite structures into account. Quantitative relationships between solidification conditions and steel-dendrite morphology are discussed first, based on steady state uni-directional solidification experiments. A new idea is proposed as Solidification-Unit-Cell, which is applied to a numerical treatment of relationship between dendritic structure of manganese-sulfide inclusions and solidification conditions. Diameter of dendritic II-type manganese-sulfide rods is correlated to a solidification parameter: R^-mG^-n which originally is related to steel-dendrite arm spacings, whereas stretches of the inclusions are related to the size and shape of residual melt pool, and amounts of constituent elements supplied thereinto.