Effect of Electropulsing Cyclic Baking Process on Microstructure and Mechanical Properties during Hot Compression for 7050 Aluminum Alloy

Abstract

In the present study, transmission electron microscopy (TEM), differential scanning calorimeter (DSC), and electron back-scattered diffraction (EBSD) were performed to investigate the effect of electropulsing cyclic baking process on microstructure and mechanical properties during hot compression for 7050 aluminum alloy in detail. The novel ECB process was compared with traditional furnace heating (FH). The results show that the quantity and size of precipitation under the FH condition were smaller than those in ECB condition, with temperature positively correlating to precipitation. The ECB process could efficiently promote the nucleation and growth of η’ and η phases. In the ECB/160 °C sample, a high density of η’ and a few η phases were observed, while the ECB/180 °C sample exhibited a large number of η phases, with nearly no η’ precipitates in the Al matrix. Additionally, the fraction of low-angle grain boundaries (LAGBs) and medium-angle grain boundaries (MAGBs) increased with the aging temperature, with higher values in the ECB samples compared to the FH samples at the same temperature. Both continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) occurred during both ECB and FH processes, and high fraction recrystallization was obtained through reducing the nucleation energy required for recrystallization through electropulsing cyclic baking process. The ECB samples exhibited superior strength and plasticity compared to the FH samples. Specifically, the ultimate tensile strength, yield strength, and elongation of the ECB/160 °C sample were 436 MPa, 538 MPa, and 12.56%, respectively, demonstrating excellent overall mechanical properties.