The effect of constrained groove pressing on grain size, dislocation density and electrical resistivity of low carbon steel

In this research, constrained groove pressing (CGP) technique is used for imposing severe plastic deformation (SPD) on the low carbon steel sheets. Using transmission electron microscopy (TEM), X-ray diffraction (XRD) and optical microscopy, the microstructural characteristics of produced sheets are investigated. The results show that CGP process can effectively refine the coarse-grained structure to an ultrafine grain range. Dislocation densities of the ultrafine grained low carbon steel sheets are quantitatively calculated and it is found that the CGP can effectively enhance the dislocation density of the sheets. Measurements of their electrical resistivity values show that microstructure refinement and increasing the dislocation density can efficiently increase the electrical resistivity of the CGPed sheets up to ∼100%.

Research highlights
► Four passes of constrained groove pressing leads to cell size of 230 nm.
► The constrained groove pressing can effectively enhance dislocation density.
► Constrained groove pressing can increase the electrical resistivity up to ∼100%.