EVOLUTION OF MICROSTRUCTURE AND MECHANICAL PROPERTIES OF ULTRA-FINE-GRAINED INTERSTITIAL-FREE STEEL PROCESSED BY EQUAL CHANNEL ANGULAR PRESSING

Equal channel angular pressing (ECAP) is one of the severe plastic deformation techniques which is widely used for producing metals with ultra- ne-grained microstructures. In the present work the influence of number of pressing by route BC on grain size, evolution of microstructure and mechanical properties of interstitial-free (IF) steel has been investigated by means of optical microscopy, electron back-scattering diffraction (EBSD) and tensile tests. It has been found, that the grain size decreases with increasing number of passes. Simultaneously tensile strength increases. The thermal stability of ECAP-processed microstructures has been also examined. It was found that the degradation of mechanical properties occurs only above 600 C and 700 C.