Plastic forming of the equal-channel angular pressing processed 6061 aluminum alloy

Abstract

Plastic formability of the ECAP processed 6061 Al alloys with ultrafine grains was examined at relatively low forming temperatures in range between 443 and 553 K. The ECAPed 6061 Al alloys after 8 and 12 passes with submicron size grains and high fractions of high angle boundaries exhibited excellent forging and micro-extrusion abilities. High quality surface was another advantageous feature of the ECAP processed samples. Compressive forging on the 8 passes 6061 Al at 523 K, however, resulted in sharp decrease in strength due to dynamic recovery accelerated in the ultra-fined (sub)grained structure. Micro-extrusion on the 12 passes 6061 Al with 2 mm in diameter was successful at 443 and 553 K. Extrusion without losing the high strength gained through using ECAP, however, could be realized only at 443 K, indicating that high strength components could be made out of the ECAPed 6061 Al using plastic working when the processing temperature was chosen to be much lower than the conventional forging temperature of ∼753 K.