Abstract: In order to achieve the effective control of titanium inclusion for the high strength tire cord steel，the properties of titanium inclusion in tire cord steel of different strength grades were explored by thermodynamic analysis combined with vacuum induction furnace experiment. The results are as follows: 1) The driving force of titanium inclusion precipitated in tire cord steel of different strength grades are different. The higher strength of the tire cord steel, the greater supersaturation of the titanium inclusion formed elements, thus the driving force of “nucleation-precipitation-grow up” becomes greater, and more helpful for the precipitation and grow up for titanium inclusion. 2) Titanium carbide and titanium nitride inclusions are existed simultaneously in the tire cord steel. The molar fraction of titanium carbide in titanium inclusion phase increased with the increasing of strength grade, and the color of titanium inclusions under the metallographic microscope are also changed. 3) The higher strength grade of tire cord steel, the larger average size of titanium inclusion precipitated during solidification, and the number of large titanium inclusions are also more. In order to effective control the precipitation of titanium inclusion in the super high strength grade tire cord steel, more strict measures of steelmaking and continuous casting process must be implemented.

Key words: tire cord steel, titanium inclusion, supersaturation, vacuum induction furnace