Three-Dimensional Microstructures and Tensile Properties of Pure Iron During Equal Channel Angular Pressing

Commercial pure iron billets having diameter of 60 mm and length of 180 mm were subjected to equal channel angular pressing (ECAP) at 350 °C for 1 to 4 passes via route Bc. Microstructural evolutions on three planes (X, Y, Z planes) were characterized by optical microscopy and transmission electron microscopy (TEM). It was found that after four passes an ultrafine microstructure could be formed on the X plane, but a band structure remained on the Z plane. Accordingly, the mechanical properties exhibited apparent dependence on the orientations. The strength in the x and y directions was higher than that in the z direction. The microstructural refinement and mechanical properties were discussed in terms of experimental results.