Equal channel angular extrusion (ECAE) is a technique that induces severe plastic shear deformation without changing the cross-sectional shape of the workpiece. As this forming technique greatly refines the grain size, it is an effective method of obtaining materials with high strength and toughness. Many researches have been done for the study of ECAE process and material behavior but not for a design rule of ECAE process. Therefore, this study proposes a design rule of an effective ECAE process for the practical application by investigating the ECAE process using finite element (FE) simulations.
The forming simulation tool, CAMPform-3D, based on the rigid thermo-viscoplastic approach and constant shear friction model, was currently used to simulate the ECAE process. The accuracy of FE simulation results was verified through comparison of numerical data with experimental findings. Experiments with commercially-available pure titanium (CP-Ti) specimen with a circular cross-section were carried out. Since the friction condition at the die and workpiece interface directly affects the forming load requirement and deformed shape in the ECAE process, it was currently evaluated by comparing the measured forming load and deformed shape obtained from experiments with simulation results.
Among various ECAE process parameters, the die corner angle and processing route are main factors which have significant effect on the strain distribution and consequently the mechanical quality of the final product. Thus, the effect of these parameters on the strain distribution was currently examined using FE analyses. The relationship between strain distribution and material properties was investigated from tensile test of the ECA extruded specimen. Based on these findings, a design rule for obtaining desirable mechanical properties in the ECAE process is proposed in the present investigation.