25 research outputs found
Strain-path effects on the evolution of microstructure and texture during the severe-plastic deformation of aluminum
The article of record as published may be found at http://dx.doi.org/10.1007/BF02586120Microstructure and texture evolution during the severe-plastic deformation (SPD) of unalloyed
aluminum were investigated to establish the effect of processing route and purity level on grain
reļ¬nement and subgrain formation. Two lots of aluminum with different purity levels (99.998 pct Al
and 99 pct Al) were subjected to large plastic strains at room temperature via four different
deformation processes: equal-channel angular extrusion (ECAE), sheet rolling, conventional conical-die extrusion, and uniaxial compression. Following deformation, microstructures and textures
were determined using orientation-imaging microscopy. In commercial-purity aluminum, the various
deformation routes yielded an ultraļ¬ne microstructure with a ;1.5-mm grain size, deduced to have
been formed via a dynamic-recovery mechanism. For high-purity aluminum, on the other hand, the
minimum grain size produced after the various routes was ;20 mm; the high fraction of high-angle
grain boundaries (HAGBs) and the absence of subgrains/deformation bands in the ļ¬nal microstructure suggested the occurrence of discontinuous static recrystallization following the large plastic
deformation at room temperature. The microstructure differences were underscored by the mechanical
properties following four ECAE passes. The yield strength of commercial-purity aluminum quadrupled,
whereas the high-purity aluminum showed only a minor increase relative to the annealed condition.Air ForceNational Science FoundationAir Force Office of Scientific ResearchContract no. F33615-03-D-5801 (AF)Grant no. DMR-02343331 (NSF)FA9550-04-1-0018 (AFOSR