By analysis on structure of low carbon Nb-V micro-alloying CB890QL steel with control-rolling from 305 mm x315 mm mediate bloom by continuous rolling speed 0. 6 ~0. 8 m/s at 950 ~ 1 028 °C

it is obtained that the dynamic recovery of the tested steel is mainly in rolling process

with the rolling speed of 0. 8 m/s

as the rolling temperature is reduced from 1 028 X. to 950 °C

the grains of steel are refined continuously

and there is also a big difference in grain size. With the rolling speed 0. 6 m/s in Φ 200 mm steel

the grain size does not change linearly with the decrease of temperature. When the continuous rolling temperature is 980 °C and the rolling speed is 0. 6 m/s

the fine and uniform microstructure of test steel can be obtained.