Exploring hydrogen effect on the formability of 3rd generation advanced high- strength steels - RAVENTOS - PID 41398 - ID11

Hydrogen embrittlement is a key limitation for advanced high-strength steels (AHSS) where retained austenite (RA), dislocation density, and vacancy-type defects determine
fracture behaviour. In the H2FORM3G project three automotive grades (DP780-GI, Fortiform®1180-GI, CP1200CH-GI) are investigated, which differ in RA fraction,
martensite morphology, and defect populations. A major open question is how hydrogen interacts with microstructural constituents and lattice defects during loading, and
how this affects crack propagation. To study this, three complementary methods are considered on samples prepared with and without hydrogen charging. High-energy
synchrotron X-ray diffraction (XRD) at ESRF provides in-situ, spatially resolved data on RA stability, elastic lattice strains, and dislocation densities ahead of crack tips. These
measurements quantify changes in phase balance and strain localisation under hydrogen but do not detect vacancy-type defects. To access this information