Canadian researchers have used the Canadian Light Source synchrotron to capture 3D views of the cracks formed in steels from hydrogen embrittlement.
The research, which was published last month in the journal Engineering Failure Analysis used the Canadian Light Source (CLS) at the University of Saskatchewan (USask) used micro-computed tomography (micro-CT) imaging to image the cracks. Researchers have previously relied on two-dimensional imaging techniques, which do not provide the same detail made possible with synchrotron radiation.
Hydrogen is increasingly gaining attention as a promising energy source for a cleaner, more sustainable future. Using hydrogen to meet the energy demands for large-scale applications such as utility infrastructure will require transporting large volumes via existing pipelines designed for natural gas.
Steel weakens when hydrogen atoms enter it by diffusing into its microstructure, causing the metal to become brittle and making it more susceptible to cracking. Hydrogen can be introduced into the steel during manufacturing, or while the pipeline is in service.
The research team studied different pipeline steels and showed that microstructure plays a critical role in how much hydrogen the steel absorbs and how it is distributed in the metal.
Their research also revealed that when hydrogen enters the steel while the pipeline is in service, it causes more damage than if introduced during manufacturing or other pre-charging conditions.
The risk of steel failure due to hydrogen embrittlement depends on several factors such as the amount of hydrogen in the steel, the steel’s microstructure, stress conditions, and operating environment.
However, USask researcher Tonye Jack emphasized that how much hydrogen is retained in the steel and where it accumulates largely dictates its failure behavior. “We need to know the mechanism of failure and how to mitigate it,” he said.
The team’s findings are important as industries plan to transport hydrogen gas using high-strength natural gas pipelines. “These findings can help inform the production of safer pipelines.”
By refining the microstructure, manufacturers can design steels that are more resistant to cracking and hydrogen embrittlement.
“We tend to look at this as one failure is too many because of their economic importance,” says Tonye. “But the bigger concern is environmental, as pipeline failures can have devastating consequences.”
As society transitions to cleaner fuels, understanding the interaction of hydrogen and steel and mitigating hydrogen embrittlement is crucial to ensuring the safety and reliability of future hydrogen infrastructure, and of great importance to the global energy framework.
