Structure and properties of low-carbon steel after deformation to high strains

The results of tensile tests carried out at various stages of deformation of a low-carbon steel by cold rolling are compounded to show the overall changes in mechanical properties during the process, which are then interpreted in terms of microstructural and fracto graphic changes. The rise in tensile stress with increasing rolling strain is essentially linear, with a plateau over a narrow strain range corresponding to a break up of the pearlite structure and the loss of its contribution to the strength. The linear increase in stress with further strain is associated with the formation of an increasing number of microbands within the ferrite portion of the structure where most of the strain is accommodated. A model is proposed for the formation of the microbands which is consistent with the observations. The microstructural changes with increasing strain are similar but not identical to those reported recently in pure copper.