Grain Precipitation and Growth Model of TiN Inclusions in 22MnB5 Steel

The accurate control of TiN particle size plays an important role in the control of slab quality. A model which can accurately predict the size of TiN particles in a slab is established by thermodynamic calculation and experimental investigation. The precipitation behavior and mechanism of TiN particles in 22MnB5 steel are clarified. The result shows that TiN particles begin to precipitate in the solid-liquid two-phase region during solidification, and the initial precipitation temperature is 1741 K (solid fraction is 0.912). With the increase of cooling rate, the particle size of TiN inclusions decreases greatly. The increase of Ti and N content will lead to the advance of precipitation time and increase of particle size. However, the effect of nitrogen content on the precipitation temperature and particle size of TiN is much greater than that of titanium content. Therefore, the size of TiN particles can be controlled in an appropriate range by reasonably controlling the cooling rate of continuous casting and the content of Ti and N in steel.