Abstract: 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.

Key words: Steel Q345C, Concasting Slab, Hot Ductility, Reduction of Area, Deformation Rate

摘要： 用Gleeble-2000热模拟机研究了Q345C钢250 mm×1 300 mm连铸坯热履历-连铸坯冷却过程和冷坯加热过程(300～1 320℃)的温度变化,应变速度(3～3×10-4 s-1)和降温速率(1～20℃/s)对热塑性的影响。结果表明,Q345C钢从1320℃冷却到钢的第Ⅲ脆性区,冷却速度越高,钢在第Ⅲ脆性区塑性越差;在600～850℃,连铸坯冷装加热后的热塑性要好于从液态直接冷却到这个温度区间的热塑性;在钢的第Ⅲ脆性区内,钢的热塑性随变形速率增大而变好。

关键词: Q345C钢, 连铸坯, 热塑性, 断面收缩率, 变形速度