Warm Forming of an AA5754 Component for Railway Vehicle Applications

In the present work, the design of the warm forming of a component in AA5754-O for railway vehicle applications is proposed: the increase of the working temperature overcomes the big limitation of aluminium alloys in terms of poor formability. The design of the process started from the characterization of both the mechanical and the strain behaviour of the alloy under investigation: tensile tests and formability tests, carried out in warm conditions (up to 250°C) provided the necessary data to be implemented within the numerical model created with the commercial Finite Element (FE) code Abaqus. The numerical activity was arranged according to an uncoupled thermo-mechanical approach: a preliminary mechanical simulation of the forming process at room temperature was run in order to evaluate the critical regions. Subsequently, thermal simulations of the heating up of both the tools and the blank were conducted to design the heating system in order to achieve a temperature distribution as uniform and close to the target (according to the results of the material characterization) in the blank deformation zone. Nodal temperature distribution coming from the thermal simulation was imported as a boundary condition into the subsequent mechanical step: strain severity was locally evaluated implementing the forming limit curves at different temperatures within the Abaqus FE model. Simulations results were subsequently validated performing experimental trials, confirming the beneficial effect of adopting warm conditions to avoid the risk of rupture: thus a sound component was successfully manufactured.