HISCC UHSS - Improvement of hydrogen induced stress corrosion cracking resistance of ultra-high strength steel screws and fasteners

The project focuses on the development and testing of ultra-high strength steels (UHSS) for bolts and fasteners. On the part of steel development screws of strength class 14.9 (tensile strength 1400 MPa and yield strength 1260 MPa) or even higher can be produced by quench and temper as well as bainitic heat treatments. A critical point in this strength class, however, is the increasing susceptibility to hydrogen embrittlement (HE) and hydrogen induced stress corrosion cracking (HISCC) with strength, leading to a safety and reliability issues in automobile applications. Thus the key point of this research is the improvement of the HISCC resistance of UHSS. Therefor electrochemical hydrogen loading and mechanical testing devices will be installed and applied as well as a laboratory smelting device for new alloy development.