The transformation behavior of a Ti-bearing microalloyed steel during continuous cooling at different start cooling temperatures was investigated by means of Formastor-FII phase transformation testing instrument. The continuous cooling transformation (CCT) curves were established, and the transformation behaviors of ferrite, bainite and martensite were analyzed. The results show that the ferrite, bainite and martensite are obtained successively with the increasing of cooling rate, and the bainite and martensite can be obtained in a wide range of cooling rate, and the martensite transformation start temperature (Ms) is about 450℃. The ferrite and bainite transformation start temperature decreases with the decreasing of start cooling temperature or increasing of cooling rate, so the ferrite and bainite phase transformation is inhibited. The microstructure of the steel transforms from ferrite plus granular bainite, lath bainite plus lath martensite and then to lath martensite successively with the increasing of cooling rate; when the cooling rate is low, the ferrite is composed intragranular ferrite and grain boundary ferrite, and the intragranular ferrite nucleat on complex oxide and sulfide.
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