Microstructural evolution of equal-channel angular pressed interstitial-free steel

Equal-channel angular pressing (ECAP) belongs to advanced technologies for improving mechanical properties of materials. In the present work, the influence of the number of ECAP passes using route BC on both grain size and mechanical properties of interstitial-free steel was investigated by means of transmission electron microscopy, electron back-scattering diffraction, and microhardness testing. It was found that the grain size decreases with the increasing number of passes. At the same time, an increase in microhardness was observed. The evolution of microstructure with increasing strain imposed through ECAP, in particular the process of grain fragmentation and the formation of high-angle boundaries were also examined.