Hydrogen in metals - from fundamentals to the design of new steels (HEmS)

Hydrogen is the lightest of the elements and has some remarkable properties and uses. Its isotopes will provide the nuclear fusion fuel for humanity in the next half century. Even now, it is probably the cleanest available fuel for motor cars and its extraction from sea water using solar power and subsequent transport around the globe is mooted as a potential solutions to our energy crisis. Because of its atomic size, hydrogen is not easy to contain as it diffuses readily through the lattice of solid materials, frequently by quantum mechanical tunnelling. The problem has a darker side; hydrogen has been known for over a hundred years to cause catastrophic failure in high strength steels. All welders know to keep their manual metal arc electrodes dry to avoid the generation of hydrogen from the decomposition of water during welding. The alloys resulting from our experiments and modelling will impact directly on the fuel efficiency of the next generation of automobiles, the service lifetimes of wind turbines and pipelines and lead to the development of new valve gear, and hydrogen handling and transport systems. We expect this to lead to improved profitability of our project partners and the sustainability of UK industry. The project will develop new design procedures for ultra-high strength steels that resist embrittlement due to the presence of hydrogen for use in the above applications . This will be achieved through a series of advances in materials characterisation, testing and modelling. New experimental techniques will be developed to identify the structure of defects in engineering alloys and how they trap hydrogen. Understanding this trapping process is a key step in understanding how and why hydrogen embrittles steels. A range of modelling techniques from the atomistic through to the continuum will be developed and employed to provide detailed information about the embrittling mechanisms and how these depend on the steel microstructure. This will allow microstructures to be identified that are resistant to hydrogen embrittlement. This information will be employed to guide the development of new procedures for the design of alloys and heat treatments that result in steels that are resistant to attack by hydrogen. These techniques will be validated by processing a range of new alloys designed using our new methodology and examining their mechanical performance in the presence of hydrogen.