The constrained groove pressing technique was used for imposing severe plastic deformation on the low-carbon steel sheets. Using transmission electron microscopy, X-ray diffraction and optical microscopy, the microstructural characteristics of produced sheets were investigated. The results showed that the constrained groove pressing process could effectively refine the coarse-grained structure to an ultrafine grain range. Dislocation densities of the ultrafine grained low carbon steel sheets were quantitatively calculated and it was found that the constrained groove pressing could effectively enhance the dislocation density of the sheets. Measurements of their electrical resistivity values showed that microstructure refinement and increasing the dislocation density could efficiently increase the electrical resistivity of the constrained groove pressed sheets up to about 100%.

The Effect of Constrained Groove Pressing on Grain Size, Dislocation Density and Electrical Resistivity of Low Carbon Steel. F.Khodabakhshi, M.Kazeminezhad: Materials & Design, 2011, 32[6], 3280-6