Analysis of the micro and substructural evolution during severe plastic deformation of ARMCO iron and consequences in mechanical properties

Abstract

ARMCO iron processed by ECAP up to a maximum equivalent strain of sixteen ECAP passes following route Bc was investigated by Electron Back Scattering Diffraction (EBSD), Transmission Electron Microscopy (TEM), TEM-EBSD and X-ray Diffraction Line Profile Analysis (XRDLPA). Different values of grain size were obtained with each technique. The lower values were obtained by XRDLPA whereas, the higher values were achieved by TEM-EBSD. Dislocation densities were also calculated by different techniques obtaining values of statistically stored and geometrically necessary dislocations as a function of the deformation. All differences in values allowed a better understanding of the nature of microstructures of the materials processed by severe plastic deformation (SPD). Mechanical properties showed a considerable increment in the material strength due to the progressive reduction of the grain size because of the Continuous Dynamic Recrystallization (CDRX) mechanism and the increment in the dislocation density.