Hydrogen Embrittlement mitigation through Layered diffusion patterns in Metals

Introduction

Hydrogen embrittlement (HE) of metallic materials is one of the main challenges for the adoption of green H2 as a clean fuel. Degradation of pipelines and vessels is nowadays avoided by conservative design and material selection, but novel mitigation strategies for hydrogen embrittlement will foster cost-effective technologies.

Proposed Strategy

I envisage an Additive Manufacturing strategy to tune hydrogen diffusion as an effective and novel method to mitigate or even suppress HE. The success of this framework requires the reconsideration of modelling and experimental techniques to characterise hydrogen transport and embrittlement in metals.

Background and Methodology

My background in computational mechanics, hydrogen diffusion simulation, and Laser Powder Bed Fusion (LPBF) will guide the approach. The methodology will be enriched by innovative phase tailoring strategies and advanced computational and optimisation procedures.

Tailoring Hydrogen Diffusion

Tailoring hydrogen diffusion in steels will be accomplished by exploiting the enormous difference in diffusivity between fcc and bcc iron phases.

1. Duplex Stainless Steels (DSS) that combine austenite (fcc) and ferrite (bcc) phases are thus considered as a first option to tune diffusion paths.
2. Additionally, localized nitrogen evaporation to directly control fcc or bcc formation during micro-LPBF of High Nitrogen Steels (HNS) will be achieved by local variation of laser parameters.

Main Goal

The main goal is to protect critical regions and therefore to suppress hydrogen-assisted cracking.

Optimization of Shielding Effects

To produce shielding effects around stress concentrators, bcc/fcc “helmets” will be optimised by coupled modelling frameworks including hydrogen transport and fracture.

Assessment and Evaluation

Trapping and multiphase diffusion will be assessed by novel modelling procedures from thermal desorption and permeation experimental results. Finally, the effectiveness of the optimised tailored helmets will be evaluated by in-situ testing in gaseous H2, paving the way for resistant components to transport and store high-pressure hydrogen.