Microstructure and Mechanical Properties of Al-11.3Zn-3.2Mg-1.3Cu-0.2Zr-0.1Sr-xTi Extruded Aluminum Alloy with Different Aging Process

The influences of adding different amount of Ti (0%, 0.39%, 0.87%) and three kinds of different aging processes (T6, T6I6, RRA) on the microstructure and properties of Al-11.3Zn-3.2Mg-1.3Cu-0.2Zr-0.1Sr were investigated. Results show that an appropriate amount of Ti can effectively inhibit grain growth and thus achieve the effect of grain refinement. The contribution of dislocation density and dislocation strengthening become the biggest when Ti content is 0.39%. At the same time, the intergranular corrosion depth is the lowest when Ti content is 0.39%. Among the three aging processes, the alloys reach the greatest hardness and tensile strength in T6I6. The biggest tensile strength reaches 716.77 MPa. However, when aging at RRA, the alloys obtain the greatest elongation, reaching 7.2%, as well as the good corrosion resistance.