Research on the local formability of Al-Mg-Si alloy sheet during rapid hot gas forming

The formation of local features in complex-shaped components is very difficult during rapid hot gas forming. To characterize the local formability of an Al-Mg-Si alloy sheet, free-bulging test and corner-filling test at different temperatures and pressurizing conditions were conducted in this study. The effects of temperature (400 similar to 500 degrees C) and strain rate (0.1 similar to 10 s(-1)) on the local formability were analyzed in detail. The local formability was reflected by the ultimate bulging ability and corner filling ability. The reason for local filling behavior was revealed from the theoretical point of view. The sheet had good bulging formability at elevated temperatures and high strain rates. The ultimate bulging ability was almost similar to the decreasing diameter of bugling die. The ultimate strain could reach 0.78 when the temperature was 500 degrees C, the strain rate was 1.5 s(-1), and the diameter of the bugling die was 10 mm. The filling ability increased as the temperature and pressure increased. A corner radius of 2.50 mm was obtained within 1 s when the temperature was 500 degrees C and the pressurizing rate was 10 MPa/s. In practice, complex-shaped components with local features could be formed within several seconds by hot gas forming.