Investigation about the oil pressure rate in the warm hydroforming of an al-mg alloy component

In this work, the hydroforming process in warm conditions was used for manufacturing an Al-Mg alloy (AA5754) benchmark component displaying different strain levels due to its geometry. The attention was focused on the effect of the rate to increase the forming pressure (PR), strictly related to the strain rate the material is subjected to. In fact, preliminary tensile and Nakajima tests (both at room temperature and in warm conditions) revealed that the mechanical and formability properties of the investigated alloy are strongly affected by the strain rate. Warm Hydroforming tests were conducted in order to investigate both the working temperature and the parameter PR. The Blank Holder Force profile was varied according to an experimentally determined profile able to avoid oil leakages. Experimental results were collected in terms of output variables related to the die cavity filling and to the strain level reached on the component: in such a way a multi-objective optimization could be carried out using the commercial integration platform modeFRONTIER. The best compromise between the high level of the component deformation and the cycle time could be obtained by conducting the warm hydroforming process at the temperature of 250°C and setting the parameter PR equal to 0.1 MPa/sec.