Impact of hydrogen incorporation on electronic and magnetic structure of X2CrNi18-9 stainless steel

TL;DR

This study investigates how hydrogen incorporation affects the electronic and magnetic properties of X2CrNi18-9 stainless steel, revealing nanoscale inhomogeneities and changes in thermodynamic stability, which could inform future steel design for hydrogen resistance.

Contribution

It provides new insights into the electronic and magneto-structural effects of hydrogen in stainless steel, using advanced neutron scattering and microscopy techniques.

Findings

Hydrogen alters the Seebeck coefficient of the steel.

Nanoscale inhomogeneities increase with hydrogen incorporation.

No direct link found between electronic/magnetic properties and dislocation density.

Abstract

Hydrogen absorption significantly alters the mechanical properties of steel. However, absorbed hydrogen also influences its electronic and magneto-structural properties, helping to interpret how hydrogen is incorporated. This study therefore investigates the influence of hydrogen incorporation on the electronic and magneto-structural properties of X2CrNi18-9 stainless steel in different microstructural states. Microstructural characterization included analytic electron microscopy mapping, X-ray diffraction and thermodynamic stability maps to evaluate grain size, dislocation density and chemical homogeneity. The electronic properties were characterized using the Seebeck coefficient, while the magneto-structural properties were investigated using diffuse neutron scattering and small-angle neutron scattering (SANS). Hydrogen incorporation showed clear changes in the Seebeck coefficients. Magnetic SANS in conjunction with diffuse neutron scattering indicates the existence of nanoscale inhomogeneities with the same fcc structure as the bulk, but with correlation lengths of a few nanometres. The size of these inhomogeneities increased with hydrogen incorporation, suggesting that hydrogen preferentially accumulates in their vicinity. However, no direct correlation between the electronic and magneto-structural properties and the dislocation density could be demonstrated. We suggest that studies such as these will lead in the medium term to the development of guidelines for material design to make steels more resistant to hydrogen.