Effect of solid solution process on microstructure and properties of 7055 aluminum alloy

In the hot extrusion process of 7055 aluminum alloy, lower forming temperature and slower extrusion speed led to the poor solid solution effect after extrusion. In order to take full advantage of the properties of high-strength alloys, off-line solution treatment was required. Firstly, by scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and electron backscattering diffraction(EBSD), the second phase distribution, grain orientation and morphology of 7055 high-strength aluminum alloy helical profile in different single-stage solution systems were studied. Secondly, through microhardness test and tensile test, the influence of solution systems on its mechanical properties was explored. Finally, the effect of solution systems on its corrosion resistance was studied by electrochemical corrosion test. The results show that with the increase of solution temperature, the second phase in the original homogeneous and extruded alloys dissolves gradually. At the same time, the grains become coarser and the equiaxed recrystallized grains grow. With the prolongation of solution time at 470 ℃, the partial phase dissolves and the degree of recrystallization increases. The corrosion resistance of the alloy increases firstly and then decreases with the increase of solution temperature and time. At 470 ℃/60 min, the optimal mechanical properties of the alloy are obtained, with the Vickers hardness of 210.5, the tensile strength of 683 MPa, the yield strength of 637 MPa, and the elongation of 15.0%. The self-corrosion potential is -0.737 1 V, and the self-corrosion current density is 6.41×10-7 A/cm2. © 2021, Central South University Press. All right reserved.