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MM: Fachverband Metall- und Materialphysik

MM 26: Topical Session: Hydrogen in Materials: from Storage to Embrittlement IV

MM 26.3: Talk

Tuesday, March 19, 2024, 14:00–14:15, C 130

Hydrogen redistribution during electrochemical charging and mechanical testing: insights from a combined ab initio and finite element method — Christian Posch-Peperkorn¹, Philipp Hammer¹, Vsevolod Razumovskiy¹, Werner Ecker¹, Klemens Mraczek², Ali Tehranchi³, and •Tilmann Hickel⁴ — ¹Materials Centre Leoben Forschung GmbH, Austria — ²voestalpine Stahl GmbH, Linz, Austria — ³MPI für Eisenforschung Düsseldorf, Germany — ⁴Bundesanstalt für Materialforschung und -prüfung, Berlin, Germany

In advanced high strength steels the mechanisms of hydrogen embrittlement are expected to be strongly connected to the amount of retained austenite (RA) contained in the microstructure and its transformation upon deformation. We have developed a multi-scale model for the H redistribution during H charging and tensile loading within a martensitic/austenitic microstructure. Ab initio simulations have been used to resolve the complex energy profile of H in the phase boundaries. Representative microstructures with different amounts of RA have been converted form experimental SEM-EBSD measurements. Simulations with the finite element method (FEM) have been used to analyse H concentration profiles. The simulations confirm an accumulation of H within the austenitic phase during charging, which undergoes a phase transformation under mechanical load and releases accumulated H into the martensite matrix. The latter segregates to the microstructure regions subjected to high hydrostatic tensile stresses and plastic strains, driving H embrittlement.

Keywords: ab initio; FEM simulation; retained austenite; hydrogen embrittlement