Diffusion-controlled recrystallization and grain growth-induced plasticity of steel under externally applied stress

Abstract

Permanent deformation, which occurs during recrystallization and grain growth under an applied stress much smaller than the yield stress of the material, was observed by dilatometric measurement and modelled on the basis of a migrating grain boundary diffusion mechanism. The observation confirmed that the transformation-induced deformation accompanying the interface migration is described by migrating boundary-induced plasticity rather than internal stress caused by volume change and plastic yielding. In the model, atomic diffusion along the migrating grain boundary was assumed to cause recrystallization and grain growth-induced plasticity. A constitutive equation for recrystallization and grain growth-induced plasticity was derived as a function of the grain growth rate, temperature and externally applied stress. The predictions were compared with the dilatometric measurements made during recrystallization and grain growth of an extra low-carbon steel under various levels of uniaxial compressive stress, with good agreement being found between the calculated permanent strain and the experimentally derived strain.

Keywords:

• boundary diffusion
• boundary migration
• recrystallization
• grain growth
• permanent strain

Acknowledgements

This work was supported by a Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MOST) (R0A-2007-000-10014-0).