Thermodynamic Research on the Precipitation of Ti2O3, TiN and TiC in Continuous Casting of Titanium Microalloyed Steel

Abstract

The composite precipitation of Ti2O3 + TiN during continuous casting has an important influence on the microstructure and properties of the slab. In order to study the precipitation conditions of Ti2O3, TiN and TiC second phase in titanium microalloyed steel, the solid-liquid phase line temperature, the initial precipitation temperature of different second phase, the equilibrium and actual solubility product of Ti2O3, TiN and TiC at different temperatures are calculated, and the precipitation rules of titanium microalloyed steel in liquid steel and two-phase region are analyzed. The results show that: Ti2O3 and TiN can precipitate in molten steel, and the precipitation order of Ti2O3 is prior to that of TiN, while TiC does not precipitate. Due to the enrichment of Ti, O, C and N in the liquid phase during solidification, the equilibrium precipitation conditions of Ti2O3 and TiN are reached when the temperature is lower than 1469°C of the liquidus, and the precipitation begins at the initial stage of solidification. When the temperature in the two-phase region is lower than 1332°C, the precipitation of TiC begins.