| Abstract: | Tube hydroforming (THF) is a relatively new but established technology among metal tube forming processes. It is the technology of forming closed sections, hollow parts with different cross‐sections by applying an internal hydraulic pressure and sometimes additional axial compressive loads to force a tubular blank to conform to the shape of a given die cavity. Material properties have a significant influence on the process stability. Often roll‐formed, non‐heat treated tubular materials made of steel with longitudinally oriented welding lines are used in tube hydroforming. Different production processes involve a change of the material properties from the initial flat sheet to the hydroformable tube. Testing methods such as tensile tests and conventional forming limit diagrams do not accurately reflect the state of stress and strain conditions seen in the tubular blank during the hydroforming process. Thus, inaccuracies in FEA predictions and design failures occur. Test methods were developed to characterize the relevant geometrical and mechanical properties of tubular semi‐finished products. |
