Effects of grain size on the dynamic recrystallization of 25Cr2Ni4MoV steel for a super-large nuclear-power rotor

The effects of grain size on the dynamic recrystallization of 25Cr2Ni4MoV steel for a super-large nuclear-power rotor were investigated on a Gleeble-1500 thermal-mechanical simulation tester with the temperature range of 1373 K-1523 K and the strain rate range of 0.005-0.5 s -1 .It was found that the flow stresses with fine grains are greater than those with coarse grains under certain deformation conditions.At high temperatures and strain rates, the DRX of the alloy with coarse grains is complete, while that of the alloy with fine grains is incomplete.In particular, the smallest DRX grain size is about 22 μm.The reconstituted microstructure by DRX with an initial grain size of 22 μm shows no refinement.Finally, it can be deduced that the model can precisely predict the rate of DRX for 25Cr2Ni4MoV steel by comparing experimental results and predicted results about the flow stress.