Analysis of the effect of material properties on the hydroforming process of tubes

The free-expansion hydroforming of tubes is discussed. Different steel grades have been studied by means of experiments, FEM simulations and a simple analytical model. The effect of different material parameters, such as the r-value and the n-value, on the hydroformability of tubes is discussed. Applying the analytical model, the favourable shape of a free-expanded tube is predicted and a ranking of different grades based on this model is proposed.