Grain refinement and tensile deformation of AA5083 sheet metals processed by ECAP
Plastic deformation of ultrafine-grained (UFG) aluminum alloys at elevated temperatures is often controlled by cooperative grain boundary sliding. In this study, we investigate the evolution of microstructure and grain size distribution of an AA5083 aluminum sheet metal after Equal-Channel Angular Pressing (ECAP) and we evaluate the resulting potential for (super-)plastic sheet metal forming. Stacks of aluminum sheets were successfully deformed by single and multiple passes in a 90° ECAP die and were subsequently characterized via electron backscatter diffraction (EBSD) and uniaxial tensile testing, respectively. Severely deformed conditions of the sheet material show different stages of grain refinement up to a fully homogeneous UFG microstructure after 4 ECAP passes following route C. Tensile tests of the ECA-processed material conditions, performed in a temperature range from room temperature to 300 °C, reveal increasing maximum tensile strains with increasing number of ECAP passes at moderately elevated temperatures. Furthermore we show that the maximum tensile strains can be further increased by a suitable subsequent stabilization annealing treatment. These results highlight the potential of stabilized ECA-processed AA5083 sheets for (super-)plastic sheet metal forming at relatively low temperatures.