Granular medium-based tube press hardening

More about the book

This thesis explores the use of granular materials as a forming medium in the press hardening process for tubes and profiles, contrasting it with fluid mediums that have hydrostatic properties. It aims to investigate this novel metal forming process and extend its limits. The study begins by evaluating the performance of granular materials and identifying criteria for selecting suitable types. A calibration procedure for the material model is introduced, utilizing instrumented die compaction tests and high-pressure direct shear tests for characterization. The flow behavior of 22MnB5 material, crucial for numerical modeling, is assessed through a self-designed hot tensile test. To enhance understanding of the pressure transfer mechanism, an analytical model is developed alongside a fully-coupled thermal-mechanical finite element model for tube press hardening using granular mediums. Experiments with a T-shaped 22MnB5 tube are conducted, and axisymmetric tube press hardening experiments are designed to define process limits through finite element simulations and experimental investigations. This research establishes foundational knowledge for an innovative granular medium-based press hardening process and proposes an alternative passive forming method, highlighting its potential for producing high-strength, high-stiffness components in lightweight automotive construction.