Effects of heat treatment on microstructure and properties of Al-5.12Mg alloy

The effects of annealing heat treatment on the microstructure and properties of cold-rolled Al-5.12Mg alloy strip were investigated by means of electron backscattered diffraction(EBSD), cupping test and so on. The results show that annealed at 250-450℃ for 1 h, the Al-5.12Mg alloy strip recovers at 300℃. The strip in the state of recovery still retains the fibrous structure with a few fine recrystallized grains, and has strong cold-rolled texture. The strip is not fully recrystallized when annealed at 350℃ for 1 h, and the orientation density of cold-rolled texture reduces and Goss textures are formed at the same time. The strip has the best overall performance in this state, with the tensile strength of 344.8 MPa, the elongation after breaking of 19.8%, the strain hardening exponent(n) of 0.27, and the erichsen value(IE) of 7.10 mm. With the increase of the annealing time at 350℃, the strip recrystallizes completely and forms a recrystallized texture based on the Cube texture. The recrystallized texture has an inhibitory effect on the grain growth. The average recrystallized grain size of the strip is the smallest at 5.88 μm when annealed at 350℃ for 3 h. As the annealing time increases, the strip's strength reduces firstly and then remains unchanged; the elongation after breaking generally increases at first and then decreases; the n increases to 0.35 and remains stable, and the IE decreases slightly. The annealed Al-5.12Mg alloy strip which has good deep-drawing formability, mechanical properties and oxidation coloring properties can meet the production and use requirements of metal buttons. © 2020, Central South University Press. All right reserved.