USask researchers use synchrotron light to capture 3D images of cracks that form inside steel.
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.
But there’s a catch. Hydrogen can weaken the steel that these pipelines are made of. When hydrogen atoms enter the steel, they diffuse into its microstructure and can cause the metal to become brittle, making it more susceptible to cracking. Hydrogen can be introduced into the steel during manufacturing, or while the pipeline is in service transporting oil and gas.
To better understand this problem, researcher Tonye Jack used the Canadian Light Source (CLS) at the University of Saskatchewan (USask) to capture a 3D view of the cracks formed in steels. Researchers have previously relied on two-dimensional imaging techniques, which don’t provide the same rich detail made possible with synchrotron radiation.
Tonye, a PhD candidate in USask’s Department of Mechanical Engineering, and his colleagues 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, Tonye emphasizes 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 says.
While catastrophic pipeline failures are rare, his 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,” he says. By refining the microstructure, manufacturers can design steels that are more resistant to cracking and hydrogen embrittlement.
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