Hot deformation and processing maps of Al-Zn-Mg-Cu alloy under coupling-stirring casting

Compression tests of direct-chill (DC) casting and coupling-stirring (CS) casting Al-Zn-Mg-Cu alloy have been performed in the strain rate range from 0.01 s(-1) to 10 s(-1) and the temperature range from 320 degrees C to 480 degrees C. The effects of DC casting on the processing map, flow behavior and deformation kinetic have been discussed. The result shows that the uniformity of the critical stress, the peak stress and the steady-state stress have been improved and the flow stress has been decreased significantly using the coupling stirring. The processing maps shown that the suitable deformation condition for the DC casting alloy is 0.01-0.1 s(-1) and 380-480 degrees C, and the suitable deformation condition for the CS casting alloy is 0.01-0.05 s(-1) and 320-480 degrees C and 0.05-0.5 s(-1) and 400-480 degrees C. The activation energies at the deterministic domains of the DC casting alloy and CS casting alloy are 210 kJ/mol and 185 kJ/mol, respectively. (C) 2018 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda. This is an open access article under the CC BY-NC-ND license.