Design high-performance AZ31 ultrathin strip through multi-pass electroplastic rolling without off-line annealing

The influence of the electropulsing parameters including the current density and the frequency, on the rolling force, the microstructure and the mechanical properties of AZ31 strips processed by electroplastic rolling (EPR) were investigated in this study. On the basis, the double grain refinement mechanism, combing the rapid completed static recrystallization refinement (SRX) of AZ31 strip before the roll with the subsequent dynamic recrystallization refinement (DRX) of AZ31 strips at the deformed zone, was put forward in the whole process of EPR. According to the mechanism of double grain refinement, an innovative method of the production of AZ31 ultrathin strip with excellent comprehensive properties is established and verified. The AZ31 ultrathin strip with the thickness of 0.35 mm was obtained at the optimal electropulsing parameters, and the total reduction of 69% can be obtained though only 2 continuous passes without any off-line intermediate heat treatment in the process of EPR; besides, the maximum rolling temperature does not exceed 483 K. It is indicated that the technology of EPR with the high current density of the electropulsing is one of the most potential method to improve the plastic formability of hardly-deformed metals.