Preparing for the hydrogen economy9 January 2020

Illustration highlighting the association of hydrogen (red)with dislocations in the crystal structure of steel. Credit:University of Sydney

In a world first, University of Sydney researchershave found evidence of how hydrogen causesembrittlement of steels. When hydrogen movesinto steel, it makes the metal become brittle,leading to catastrophic failures. This has been oneof the major challenges in moving towards agreener, hydrogen-fuelled future, where steel tanksand pipelines are essential components that mustbe able to survive in pure hydrogen environments.

Published in Science, the researchers found hydrogen accumulates at microstructures calleddislocations and at the boundaries between theindividual crystals that make up the steel.

This accumulation weakens the steel along thesefeatures, leading to embrittlement.

The researchers also found the first directevidence that clusters of niobium carbide within thesteel trap hydrogen in such a way that it cannotreadily move to the dislocations and crystalboundaries to cause embrittlement. This effect hasthe potential to be used to design steels that canresist embrittlement.

Lead researcher Dr. Yi-Sheng Chen from theAustralian Centre for Microscopy and Microanalysisand Faculty of Engineering at the University ofSydney said these findings were an important stepto finding a safe solution to produce, store andtransport hydrogen.

"These findings are vital for designingembrittlement-resistant steel; the carbides offer asolution to ensuring high-strength steels are notprone to early fracture and reduced toughness inthe presence of hydrogen," Dr. Chen said.

Atom probe Image showing accumulations of hydrogen(red) at carbon-rich (blue) dislocations in steel. Thisevidence underpins the theoretical prediction of the originof hydrogen embrittlement that limits the progress ofhydrogen economy. Credit: University of Sydney

Senior author Professor Julie Cairney from theAustralian Centre for Microscopy and Microanalysisand Faculty of Engineering at the University ofSydney said these findings were a positive steptowards implementing clean fuels.

"Hydrogen is a low carbon fuel source that couldpotentially replace fossil fuels. But there arechallenges with the use of steel, the world's mostimportant engineering material, to safely store andtransport it. This research gives us key insights intohow we might be able to improve this situation,"Professor Cairney said.

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Illustration highlighting the concentration of hydrogenatoms (red balls) at the crystal boundaries anddislocations in steel. Credit: University of Sydney

Working in partnership with CITIC Metal, theresearchers were able to directly observe hydrogenat microstructures in steels thanks to MicroscopyAustralia's state-of-the-art custom-designedcryogenic atom probe microscope.

More information: "Observation of hydrogentrapping at dislocations, grain boundaries, andprecipitates" Science (2020). science.sciencemag.org/cgi/doi …1126/science.aaz0122

Provided by University of Sydney

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APA citation: Preparing for the hydrogen economy (2020, January 9) retrieved 14 May 2022 from https://techxplore.com/news/2020-01-hydrogen-economy.html

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