Analysis of Temperature and Stress Distribution on the Bond Properties of Hybrid Tailored Formed Components

Processing of hybrid materials is particularly challenging due to the different physical properties and requires extensive knowledge to produce defect-free components. When serially combining steel and aluminum through rotary friction welding and subsequent cup backward extrusion in Tailored Forming, the strongly different yield stresses are a decisive factor. The following study analyzes the temperature and stress distribution after the compensatory heating step with additional cooling and during cup backward extrusion within a preform of a hybrid hollow shaft using experimental heating tests and finite element simulations. The influence on the bond strength is quantified by uniaxial tensile tests along the interface. Compared to uncooled samples, local cooled samples exhibit higher compressive stresses in the joining zone and hence higher forming resistance due to higher temperature gradients. Therefore, delamination and cracks can be prevented. While areas at the edge or in the center indicate reduced strengths overall, areas with high surface enlargement do not fail in the joining zone, but in the base material of the aluminum. To further enhance process stability and process control measures, a preliminary concept for the implicit determination of component temperatures using integrated sensor systems on the handling system is presented.