Direct Imaging of Hydrogen-Driven Dislocation and Strain Field Evolution in a Stainless Steel Grain

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Hydrogen embrittlement (HE) is a critical issue for materials in hydrogen technologies.
• Understanding nanoscale mechanisms of HE in bulk materials is experimentally challenging.
• Current methods often rely on simulations or thin samples, limiting bulk insights.

Purpose of the Study:

• To experimentally investigate hydrogen-induced dislocation behavior in bulk 316 stainless steel.
• To provide nanoscale mechanistic insights into hydrogen embrittlement.
• To validate theoretical predictions and inform multiscale modeling.

Main Methods:

• In situ Bragg coherent X-ray diffraction imaging was used to track 3D dislocation and strain evolution.
• Hydrogen charging was performed on a bulk grain of austenitic 316 stainless steel.
• Nanoscale strain analysis was employed around dislocation cores.

Main Results:

• Observed hydrogen-enhanced dislocation mobility and relaxation in bulk material.
• Documented dislocation unpinning and climb processes, potentially driven by osmotic forces.
• Quantified nanoscale elastic shielding effects induced by hydrogen at dislocation cores.

Conclusions:

• Experimental findings validate theoretical predictions of hydrogen-driven dislocation behavior.
• Mechanistic insights into HE at the nanoscale are provided.
• Data can be used for multiscale modeling to develop HE-resistant alloys.