Analysis of Transition Zone on a Hot-Stamped Part with Tailored Tool Tempering Approach by Numerical and Physical Simulation

The tailored tool tempering press hardening process (TTTPH), where the cooling rate is controlled by dividing the tools into heated and cooled zones, allows the manufacture of components with tailored properties, improving the crashworthiness in transport applications. During this process, gradual changes in mechanical properties occur on the component near the transition zone between heated and cooled zones. Herein, a finite element (FE) model of the TTTPH process is developed to simulate the manufacturing of an automotive B-Pillar in USIBOR1500P with three tailored zones, two ductile regions, and one central fully hardened region. Through FE simulations, the influence of process parameters such as transport time, quenching time, the temperature of heated tools, and the design parameter (air gap between cooled and heated tools) on the width of the transition zone and its shift with respect to tools position is investigated. Finally, experimental tests with the Gleeble-3180 physical simulator are carried out to study the mechanical properties near the transition zone. Based on FE results, as the air gap increases, the transition zone width decreases, and its shift increases. These output parameters are most affected by the temperature of heated tools. Experimental results show a gradual change in mechanical properties, confirming numerical predictions.