STRUCTURE AND PROPERTIES OF THE Al-Zn-Mg-Cu-Zr-Y(Er) ALLOYS SHEETS DOPED BY MANGANESE

Abstract

The structure and properties of rolled Zn-Mg-Cu-Zr-Y(Er) alloys alloyed with manganese and modified with titanium have been studied. According to the results of tensile tests in the deformed and annealed state at 120-150°C for one hour, AlZnMgCuMnTi and AlZnMgCuMnTiEr alloys have a high yield strength of 417-456 MPa with a small relative elongation of 2-5.2%. The presence of additional dispersant-forming elements of yttrium and erbium increases the particle precipitation density during homogenization annealing, increasing the temperature of the onset of recrystallization and the hardness of the rolled alloys. After one hour annealing at 350°С, the structure of the AlZnMgCuMnTi alloy is completely recrystallized, while recrystallization is just beginning in alloys with yttrium and erbium. After quenching from 465°C and aging at 120°C, the test alloys have a yield strength of more than 410 MPa, a tensile strength of more than 520 MPa, and an elongation of more than 10%. The obtained properties are higher than the properties of clad sheets of high-strength heat-strengthened alloy Al-Zn-Mg-Cu (B95A) and bars of AlZn4.5Mg1.5Mn and AlZnMg1.5Mn alloys and are at the level of properties of bars of Al-Zn-Mg-Cu alloy (B95).