Morphology control of MnS inclusions in steel during solidification by theaddition of Ti and Al

The morphology and distribution of MnS in Fe-0.1C-1Mn-0.02S by the addition of Ti and Al were investigated. The size of the globular monotectic MnS de creases with increasing Ti content, while the addition of Al increases the size of MnS. Moreover, the morphology of MnS changes from globular to rod-l ike forms with the addition of Al. The formation mechanism of MnS is discus sed on the basis of phase diagram information. It is shown that the changes in morphology and size of MnS depend on the nature of the oxides in melts. As Al content is increased, deoxidation products tend to be Al2O3 having a high melting point, which act as nucleation sites for the rod-like eutecti c MnS. As Ti content is increased, Ti-Mn complex oxide with a low melting p oint is formed, which finely disperses and acts as a nucleant for globular monotectic MnS.