Phase equilibrium between CaO·Al 2O 3 saturated molten CaO-Al 2O 3-MnO and (Ca, Mn)S solid solution

Abstract

Refinement of austenite grains by generating intra granular ferrite (IGF) in austenite grains is one of the most effective methods for improving the toughness of the heat-affected zone (HAZ). It is known that MnS precipitated on fine oxides enhance formation of IGF in austenite grains. Flux composed of CaO -Al 2O 3 is often used in secondary refining and Ca-Mn-Al complex oxide may form, and it is important to clarify the mechanism of MnS precipitation on oxide inclusions. Therefore, molten CaO-MnO-Al 2O 3 oxide was equilibrated with (Ca, Mn)S solid solution in Al 2O 3 crucible in an electric resistance furnace at 1 648, 1 698 and 1 748 K in the present work. Phase relation between CaO·Al 2O 3 saturated molten CaO-MnO- Al 2O 3 oxide and (Ca, Mn)S solid solution was clarified. © 2011 ISIJ.