Effects of strain, deformation temperature and strain rate on microstructure evolution of ferrite during intercritical deformation in a low carbon microalloyed steel have been studied via electron back-scattered diffraction analysis. The result shows that continuous dynamic crystallisation (CDRX) can be induced by a small strain of 0.25 when deformation temperature is 750°C and strain rate is 0.1 s−1. Increasing deformation temperature or reducing strain rate prompt the CDRX. However, CDRX is remarkably enhanced when deformation temperature is larger than 780°C even under large strain rate condition. Both the equiaxed grain sizes and sub-grain sizes of intercritically deformed microstructures are smaller than 3 μm at various process parameters. Intercritical deformation is an effect way to ultra-refine microstructure for steels.
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