The Composition and Morphology Evolution of Oxide Inclusions in Ti-bearing Ultra Low-carbon Steel Melt Refined in the RH Process

摘要

Before deoxidation, the main inclusions were Fe–Mn–O inclusions in Ti-bearing ultra low-carbon steel melt. After 3 min Al addition, the inclusions changed to be granular and spherical Al_(2)O_(3). Al_(2)O_(3) cluster, composed of granular and spherical particles with diameter 1–2 μm, formed in 7 to 10 min after Al addition into the melt. Al_(2)O_(3)·TiO_(x ) inclusions with the Ti/(Al+Ti) between 0.15 and 0.30 formed 3 min after ferro-titanium addition and Al_(2)O_(3)·TiO_(x ) cluster formed because rich [Ti] and poor [Al] regions existed around the ferro-titanium particles and Al_(2)O_(3) cluster. The Ti_(3)O_(5) was hard to be formed when acid-soluble aluminum exceeded 0.035% with titanium blow 0.08%. The activity of Ti_(3)O_(5) in the complex liquid phase inclusions increased remarkably with the decrease of acid-soluble aluminum and increase of titanium.