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

摘要

Commercial pure iron billets having diameter of 60 mm and length of 180 mm were subjected to equal channel angular pressing (ECAP) at 350 ℃ for 1-4 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.