| The effect of Si addition on the interaction between recrystallization and precipitation during multipass deformation has been investigated in terms of the no-recrystallization temperature (Tnr), the minimum temperature at which recrystallization can be completed. The Tnr was measured in three Nb microalloyed steels with Si concentrations ranging from 0.01 to 0.48wt.%. Continuous cooling conditions were employed, with interpass times of 20--200s and strains of 0.2 and 0.35 applied at a strain rate of 2s -1.;It was observed that for similar Nb contents, the Tnr increased with Si level, but appeared to saturate at long interpass times. In addition, high strains also reduced the influence of Si on the Tnr. This behaviour can be attributed to the acceleration of the Nb(C,N) precipitation kinetics by the addition of Si. With increasing interpass time or strain, the precipitates start to coarsen and, in consequence, the pinning effect due to precipitation is reduced. Therefore, under these conditions, the effectiveness of Si addition in raising the Tnr is diminished. |
