The effect of strain temperature and strain rate on critical deformation and dynamic recrystallization during single pass deformation at strain temperature between  1000 ℃ and  1100 ℃ and strain rate  1~10 s

-1

and the effect of strain temperature and inter-pass time on static recrystallization at temperature between 950 ℃ and 1050 ℃ and strain rate 10  s

-1

during  double  pass  rolling  of a  microalloyed  steel  Q345E:0.084C- 1.05Mn-0.026Nb-0.003Ti-0.007Mo-0.003V  have been studied by a Thermecmaster-Z thermal simulation machine. The test results showed that during single pass deformation the higher strain temperature was contributed to recrystallization of steel but the higher strain rate speeded up hardening of steel;during double pass deformation with prolonged inter-pass time and increased strain temperature

the static recrystallization percent increased.