Structure transformation rule of ECAP-deformed low carbon steel

Subgrain and micrograin structures of Q235 steel were obtained by the process of equal channel angular pressing (ECAP) at room temperature with the route Bc that samples were rotated 90(and kept the direction unaltered after ECAP. The microstructure evolution of four surfaces was observed after ECAP deformation. It is shown that the microstructure of ECAP deforming Q235 steel is thinned with the increase of deformation pass, and the thinning degree of the first pass is the greatest. The appearances of four surfaces are different: Surface S is mainly dislocation cells; Surface R appears the cross of deforming bands in the second pass; there are equiaxed grains on Surface T after two passes, and the grain boundaries of equiaxed grains are very clear after four passes, with an average grain size of about 0.25μm; On Surface L are equiaxed grains after four passes, and the grain boundaries are not clear. After eight passes, all surfaces are clear equiaxed grains, the average grain size is about 0.20μm. The subgrain and micrograin structures of Q235 steel can obtain by means of ECAP.