Microstructure investigations on 2A10 aluminum alloy bars subjected to electromagnetic impact upsetting

In this work, electromagnetic impact upsetting (EIU) process was proposed. And EIU and quasi static upsetting (QSU) experiments were performed with Φ6mm-2A10 aluminum alloy bars. Microstructure evolutions for both processes were revealed by metallographic observations under the varying engineering strains. Results showed that the most deformations for the EIU process significantly concentrated in narrower adiabatic shear bands (ASBs) comparing with the QSU process. The ASBs initialized in the diagonal points of samples and gradually extended to the central with the continuous deformations. And four ASBs encountered and integrated in the central. The high strain rate contributed to deformation concentration and the forming of the adiabatic shear bands. In addition, hardness values for the EIU process were higher than that of the QSU process, demonstrating that the strengthening effect of the strain rate was notable. TEM observations presented that the ASBs with the highest hardness contained many lamellar sub-grains and second phase particles (Al2Cu). The high strain rate caused that rotated sub-grains converted into dynamic recrystallization grains within ASBs. Plentiful dislocation tangles and strengthening phases accounted for highest hardness values within the ASBs.