Abstract :
Equal Channel Angular Extrusion (ECAE), developed and patented in Russia by Segal in
1977, has become in the last few years a very popular tool for studying the evolution of
microstructure and properties under severe plastic deformation. It is believed that the
strain-stress characteristics are uniform in a cross-section of the billet and this uniformity of
the stress-strain distribution ensures the uniformity of microstructure and mechanical
properties in ECAE processed billet. However, some experimental data such as the fracture
of the extruded billet, which is initiated at the inner surface of the sample, has caused
doubts about uniformity of stress-strain distribution. This non-uniformity has been proved
recently by Finite Element Simulation.
This paper reviewed our results from over six years of work using a unique machine for
ECAE with computer controlled back-pressure and velocity of the backward punch.
Theoretically back-pressure has been introduced in the earlier papers of Segal. However,
practically back-pressure has not been widely used or often used in a primitive form of the
consequent extruded sample and its role has not been understood.
C 2005 Springer Science + Business Media, Inc.
