MULTIHY

Multiscale Modelling of Hydrogen Embrittlement

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 Obiettivo del progetto (Objective)

'The proposed project aims to advance the state-of-the-art of numerical modelling of hydrogen embrittlement (HE). The primary focus and novelty of the project is the description of H transport in modern advanced materials with complex microstructures. This goal will be achieved through development of a multiscale modelling framework, which will enable the extraction and propagation of information pertaining to critical microstructural features from the nanometer level to the macro scale. The key aspect of this modelling effort is the incorporation of atomistically-derived diffusion barriers for critical H trapping sites into continuum and component level models. The gap between the atomistic and continuum hierarchies will be bridged by kinetic Monte Carlo calculations that will provide a basis for derivation of a novel set of equations for H diffusion. These equations will be applied in continuum and component models for boundary conditions representative of those that occur in service. The boundary conditions will be furnished by data collected in-service and from experimental measurements. The outcome of the modelling will be further related to degradation and reliability assessment by the determination of semi-empirical fracture criteria, which will be incorporated into the model at the component level. The modelling will be validated at all levels using advanced experimental techniques. The effectiveness of the proposed simulation framework will be demonstrated by investigating the role of microstructure in three contrasting industrial problems, which have been specified by companies involved in the development and application of advanced materials. The project represents a significant step towards a universal, engineer-oriented software tool for the evaluation of the HE susceptibility of materials and components based on real microstructural information and environmental conditions.'

Introduzione (Teaser)

When hydrogen diffuses into metals, it reduces their ability to deform under stress. A multi-scale model of related phenomena will aid numerous industries in proper selection of materials and processes to minimise hydrogen embrittlement.

Descrizione progetto (Article)

Whether hydrogen is absorbed from the environment or produced by a chemical reaction such as corrosion, the resulting hydrogen embrittlement is a costly problem for several industries. Until now, scientists did not have adequate multi-scale models describing hydrogen transport in advanced materials such as high-strength alloys with complex microstructures.

The EU-funded project 'Multiscale modelling of hydrogen embrittlement' (http://www.multihy.eu/ (MULTIHY)) is addressing this issue. Scientists are relating the effect of micro-scale and even nano-scale structural features to measurable macroscopic hydrogen embrittlement susceptibility factors. Analytical techniques, physical testing and in-service data collection are being used to develop a multi-scale integrated model of hydrogen transport from the atomistic to the component level.

Researchers have chosen three case studies covering the combustion chambers of a satellite launcher, future automobile chassis components and wind turbine bearings. The approach is to develop accurate descriptions of hydrogen trapping and diffusion. These behaviours are influenced by atomistic factors such as crystal structure and defects all the way up to macroscopic parameters such as temperature and stress gradients.

Scientists must balance and integrate the spatial and temporal differences between atomistic and finite element (FE) models to ensure accuracy without undue computational load. They are using kinetic Monte Carlo simulations to facilitate use of the results of atomistic calculations as input parameters to FE-based models. Key model parameters are deduced from experiments exploiting specially fabricated model materials with well-defined microstructures.

The team has been focusing on detailed microstructural analyses of materials for all three case studies, and evaluation of hydrogen diffusion and trapping parameters through experiments and atomistic modelling. Scientists are now integrating the models at the atomistic, meso (intermediate) and macro scales. During the final year, researchers will expand the library of input data and apply it comprehensively in detailed simulations of hydrogen-assisted failure in industrially relevant components.

MULTIHY's multi-scale modelling framework will assist companies in making informed decisions regarding the materials and processing methodologies they choose for their products. The end result will be reduced failure of advanced parts with complex microstructures due to hydrogen embrittlement and a boost to the competitive position of EU manufacturers.