CHARACTERIZATION OF DEFORMATION MECHANICS AND MICROSTRUCTURE EVOLUTION DURING INDIRECT EXTRUSION IN SMALL LENGTH SCALES

摘要

In situ characterization of mechanics of deformation including dynamic strain, strain-rate and rotation of material elements was performed in prototypical small length-scale forming operation- indirect extrusion (IE) of commercially pure Lead (Pb) and Aluminum (Al 1100) using Digital Image Correlation (DIC) technique. Effects of scaling and deformation rate over a range of dimensions and velocities on mechanical response of CP Pb and the resultant anomalies were studied. Additionally, previous and post-deformation characterization of microstructure in Al was accomplished by performing Orientation Imaging Microscopy (OIM) on workpiece materials with different grain sizes. Finally, In situ characterization aided by high speed imaging of indirect extrusion of Al coupled with a Visco-Plastic Self-Consistent (VPSC) model was used to predict the evolved textures in various regions of deformation zone and the results were compared to OIM observations.