Preparation of high-strength Al-Mg-Si-Cu-Fe alloy via heat treatment and rolling

An Al-Mg-Si-Cu-Fe alloy was solid-solution treated at 560A degrees C for 3 h and then cooled by water quenching or furnace cooling. The alloy samples which underwent cooling by these two methods were rolled at different temperatures. The microstructure and mechanical properties of the rolled alloys were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and tensile testing. For the water-quenched alloys, the peak tensile strength and elongation occurred at a rolling temperature of 180A degrees C. For the furnace-cooled alloys, the tensile strength decreased initially, until the rolling temperature of 420A degrees C, and then increased; the elongation increased consistently with increasing rolling temperature. The effects of grain boundary hardening and dislocation hardening on the mechanical properties of these rolled alloys decreased with increases in rolling temperature. The mechanical properties of the 180A degrees C rolling water-quenched alloy were also improved by the presence of beta aEuro(3) phase. Above 420A degrees C, the effect of solid-solution hardening on the mechanical properties of the rolled alloys increased with increases in rolling temperature.