42nd International Deep Drawing Research Group Conference - IDDRG 2023

The use of press-hardening steels (PHSs) in automotive bodies creates the opportunity of producing thinner but higher-strength components. PHS1800, a grade of PHSs with a strength level of around 1.8 GPa after hot stamping, is a candidate material for vehicle anti-intrusion structures. The current study aims to investigate the formability of this steel during the hot-stamping process. A novel experimental methodology was developed to characterize the Al-Si coated PHS1800 formability using a custom Marciniak punch and digital image correlation (DIC) techniques. The carrier blank thickness and geometry were exploited to quench the surrounding material of the specimens while promoting localization in the central regions. The proposed methodology provided approximately linear strain paths from uniaxial to biaxial stretching while avoiding friction and out-of-plane bending. The forming limit curves (FLC) of the material under various hot-stamping conditions were predicted using the Marciniak-Kuczyński (MK) model, taking into account the temperature and strain-rate histories. The predicted limiting strains were in good accord with the measured data.