Deformation and strengthening analysis of Al-Mg-Si alloy sheet during hot gas forming with synchronous die quenching

Abstract Hot gas forming with synchronous die quenching is proposed to form aluminum alloy complex-shaped components. The effects of heating temperature (400∼520℃), gas pressure (1∼10 MPa) and gas intake methods on the deformation behaviors of a heat treatable Al-Mg-Si alloy sheet were analysed. The temperature fields were measured to reveal the formation mechanism of defects. The final strength distributions were clarified by hardness and tensile tests to evaluate the strengthening effect of die quenching. It is found that the excellent bulging ability exhibits in the integrated process, a double-stepped box specimen with a maximum strain of 0.64 and dimensional deviation less than 0.2 mm can be formed by collaboratively controlling the closing and pressurizing processes. The heating temperature should be higher than 500℃ to avoid rupture. A gas pressure of higher than 7.5 MPa is needed to ensure full filling. The gas intake should occur in the areas with a small deformation or no deformation to avoid the effect of decreasing temperature on deformation. A sufficient cooling ability (cooling rate being above 50℃/sec) by die quenching ensures the strengthening level in T6 temper of this material. It is a huge potential to form complex-shaped components with full strength and high dimensional accuracy by hot gas forming with synchronous cold-die quenching.