Microstructure gradient after hot torsion deformation of powder metallurgical 6061 Al alloy

The microstructure and the texture of extruded 6061 Al alloy processed by powder metallurgy (PM), using three different initial powder particle sizes, have been studied after torsion deformation at 300 degrees C at strain rate of 6 s(-1). The initial extruded microstructure of the three alloys consisted of elongated grains confining substructure with a typical < 1 1 1 >+< 1 0 0 > fiber texture. After torsion deformation, the torque (Gamma) as a function of the equivalent strain (epsilon(eq)) showed softening and the microstructure exhibited a gradient across the section so that the inner and outer zones contained sheared-elongated and small-equiaxed subgrains, respectively. It was observed that the equivalent strain to failure for the material processed using powder particles size of less than 45 mu m was of about epsilon(eq) similar to 12, compared to epsilon(eq) similar to 1 for material processed using powder particles size of less than 25 mu m. The microstructural changes during hot torsion deformation of PM 6061 Al alloy should involve continuous dynamic processes.

aluminum alloy; powder metallurgy; torsion deformation; microstructure; recrystallization

Microstructure gradient after hot torsion deformation of powder metallurgical 6061 Al alloy Articles