Intragranul strains and mosaicity in alpha and gamma phases of a duplex steel during electrolytic hydrogenation

Hydrogen absorption in steel induces embrittlement, reducing tensile strength, fatigue resistance, and fracture toughness. In duplex steel, hydrogen expands the austenitic fcc crystal structure while leaving the ferritic bcc lattice unchanged. This expansion near the surface encounters resistance, leading to in-plane compressive stresses in both phases. Hydrogen uptake induces plastic deformation in austenite, contrasting with the unaffected ferrite. These findings were observed in bulk steels using in-situ high-energy X-ray diffraction. Our proposed DFXM experiment aims to deepen understanding by scrutinizing intragranular strain and mosaicity changes during hydrogen uptake in individual grains of fcc and bcc phases. The primary goal is to meticulously track hydrogen uptake by analyzing lattice parameter changes, providing unprecedented insights into the microstructural dynamics of hydrogen interaction with specific grains, grain boundaries, and defects in duplex steel.