High-throughput evaluation of alloying effect on hydrogen diffusion of ultra-high strength steel

Hydrogen embrittlement is a critical factor limiting the development of ultra-high-strength steel for automotive applications.To enhance the efficiency of alloy design for HE resistance in ultra-high-strength steel, this study presents a high-throughput approach to measure hydrogen diffusion coefficients in martensitic steels using scanning Kelvin probe force microscopy integrated with diffusion multiple techniques. By analyzing regions with varying Cr and Mo contents, we demonstrate that these solutes induce subtle microstructural changes, reducing grain size and low-angle grain boundary fractions while increasing high-angle grain boundaries. The hydrogen diffusion coefficient decreases with higher Cr and Mo contents, primarily due to lattice distortions, with Mo showing a stronger effect owing to its larger atomic radius. Supported by EBSD, HADDF, and statistical analyses, these findings elucidate the influence of solute alloying on the reduction of the hydrogen diffusion coefficient, providing a robust framework for rapid alloy screening and optimization.