Effect of Ti Addition on Non‐Metallic Inclusion Characteristics in TRIP Steel

Abstract

Herein, the effect of Ti addition on the formation and evolution of inclusions in high‐Al transformation‐induced plasticity (TRIP) steel is investigated by performing a series of laboratory experiments and thermodynamic calculations for different quantities and sequences of Ti addition. Before the addition of Al and Ti, the main inclusions are spherical Mn–Si–Al–O oxide particles. The addition of Al transforms the Mn–Si–Al–O inclusions to Al2O3 inclusion. After the subsequent addition of 0.02 wt% Ti, the main inclusions are Al2O3, AlN, Al2O3–AlN, Al2O3–TiN, and Al2O3–AlN–TiN. However, after the subsequent addition of 0.05 or 0.12 wt% Ti to molten steel, the main inclusions are Al2O3, TiN, and Al2O3–TiN, and almost no AlN is observed. Using different addition sequences of Al and Ti to high‐Al TRIP steel does not result in significant differences in the types of inclusions. Adding Ti to molten steel does not transform Al2O3 to Ti‐oxides, whereas Al addition causes Ti‐oxides to be transformed to Al2O3. Importantly, adding over 0.05 wt% Ti to TRIP steel prevents the formation of AlN inclusion.