Flexible manufacturing chain with integrated incremental bending and Q-P heat treatment for on-demand production of AHSS safety parts

摘要

This work proposes a manufacturing chain that combines the two key technologies Incremental Swivel Bending (ISB) and Quenching and Partitioning (Q-P). While incremental forming methods offer chances for production flexibility, strain hardening often exhausts material's ductility. Heat treatment processes can potentially renew the material's capability to deform. Q-P, in particular, not only erases the influence of cold forming but also delivers advanced high strength properties (AHSS). Q-P has already been proposed for the incorporation of hot forming methods; however, integration methods for cold forming techniques represent a key research gap. The combined effects of cold forming of a Q-P suitable material in its initial pearlitic structure and subsequent Q-P heat treatment are investigated in this paper. Profiles of various cross sections are manufactured from a low alloyed, carbon enriched (42SiCr) steel and bent to various geometries by the flexible ISB process. An analytic model to determine the strain distribution caused by ISB is developed and validated within the bent areas by considering strain maps, local material properties and curvature distributions. Furthermore, material properties resulting from different Q-P treatments on the previously bent sections are evaluated with respect to accelerated heating gradients from quenching to partitioning. Tensile test specimens, locally extracted from the bent arcs, confirm the elimination of any remaining strain hardening after the heat treatments. Moreover, due to considerably high ductility at high tensile strength levels, the evaluation of energy dissipated during tensile tests demonstrates the Q-P treated material's high potential to absorb energy even at elevated strain rates. The suggested manufacturing chain, combining ISB and Q-P, enables high production flexibility and delivers advanced high strength properties for the production of lightweight components, suitable for energy absorption at high strain rates, e.g. crash structures in cars.