The effect of heating history- temperature change in cooling process of concasting slab and in heating process (300 ~ 1 320℃ ) of cold slab

strain rate (3 ~3 x 10

-4

s

-1

) and cooling rate ( 1 ~ 20 ℃/s) on hot ductility of 250 mm x 1 300 mm concasting slab of steel Q345C has been studied by using Gleeble-2000 thermal/strain simulation testing machine. Results show that cooling from 1 320 ℃ to IH brittle zone

the higher cooling rate the lower hot ductility of steel in Ⅲ brittle zone； at 600 ~850℃

the hot ductility of concasting slab with cold charge practice is better than that with prctice of direct cooling from liquid to this temperature region ； and in Ⅲ brittle zone of steel

with increasing deformation rate the hot ductility of steel becomes better.