Severe Plastic Deformation (SPD) processing, especially Equal-Channel Angular Pressing (ECAP) of steel and other iron-based alloys, has achieved increasing interest recently because of the potential for obtaining ultrafine grains and improving the properties [1–8]. Shin and co-workers [1–5] have conducted extensive investigations on ECAP processing of a 0.15 wt% C commercial carbon steel, usually at 623 K using route C. A near-equiaxed ultrafine grain structure of ∼0.2 µm resulted from 4 passes of ECAP [1] and this led to a substantial increase of the yield stress (YS) to ∼937 MPa and the ultimate tensile strength (UTS) to ∼943 MPa with reasonable elongations of ∼10 % [2,3]. Investigations by Fukuda et al. [8], conducted at room temperature using route B_c, achieved an essentially equiaxed microstructure with high grain boundary misorientations and an average grain size of ∼0.2 µm with a UTS of ∼800 MPa after ECAP through only three passes. These latter experiments used a carbon steel with a fairly low carbon content of 0.08 % C and there was an extensive region of strain hardening and a reasonably high elongation to failure in tensile testing at room temperature.