Microstructure evolution during severe plastic deformation of IF steel

Severe plastic deformation of IF steel was repeatedly carried out at room temperature by using semi-continuous equal channel angular extrusion(SC-ECAE). The microstructures evolution and the mechanisms of grain refinement during deformation were analyzed by EBSD. The results showed that the deformation primarily takes place in simple shear along the intersectional plane of the two extrusion channels, the plastic deformation is caused by shear strain, and the stress of deformation structures is reasonably uniform over the whole cross-section of the workpiece. The grain refinement is strengthened with the increase of strain. The final HAB fraction of about 90% is obtained and the HAB spacing decreases to less than 1 μm, and the overall grain size decreases to about 0.55 μm after 10 passes.