A group of researchers from The University of Texas at San Antonio (UTSA) and Southwest Research Institute (SwRI) are collaborating on a project examining the hydrogen embrittlement of additive manufacturing materials.
Oil and gas pipelines will often crack once exposed to hydrogen after a certain period of time. Focusing on nickel-718, a typical alloy implemented within the oil and gas industry, the researchers will explore how hydrogen embrittlement conditions develop for when the material is processed through additive manufacturing. The aim is to establish a possible future where additive manufactured parts can be designed to be less susceptible or even immune to hydrogen embrittlement.
“By understanding more about hydrogen embrittlement of AM materials, we can provide crucial information, with more confidence, to optimize the AM and post-fabrication processes,” states Assistant Professor Brendy Rincon Troconis in the UTSA Department of Mechanical Engineering.
“[We can also] prevent brittle fracture of future and current systems, while advancing the AM technology, which will all lead to better protection of the community, its assets, and the environment.”
Preventing the degradation of AM metals
UTSA and SwRI researchers have expressed concern regarding the lack of testing into the susceptibility of additive manufacturing metal to hydrogen embrittlement, as it is a common problem that can lead to mechanical hardware degrading and losing functionality. In 2014, it caused Kazakhstan’s largest oil field to be shut down for two years due to large cracks in the pipelines.
The research team decided to focus its research on additive manufactured nickel-718 alloy, a metal suited for highly critical conditions due to its mechanical properties and corrosion resistance. For these reasons, the metal material is often employed in the oil and gas industry, where 3D printing is demonstrating continued implementation from major entities within the sector.
Professor Rincon Troconis from UTSA will collaborate with W. Fassett Hickey of SwRI’s Mechanical Engineering Division to understand the impact of hydrogen embrittlement on the integrity of additive manufactured nickel-718. Their research will involve the inspection of hydrogen embrittlement on a molecular level, as the process only occurs in oil fields when pipeline materials and down-hole tools absorbs atomic hydrogen. Both researchers aim to observe how the location of hydrogen atoms influences the structure of the metal, particularly when placed under the high pressures and elevated temperatures typical of drilling environments.
SwRI’s testing facilities will allow the researchers to perform mechanical testing in gaseous hydrogen up to 3,000 PSI and 500 °F. UTSA will provide its thermal desorption spectrometer and scanning kelvin probe force microscope to help further understand hydrogen-alloy interaction. Hickey suggests that once their research is complete, applications for additive manufacturing materials could be expanded. “If we can better understand the underlying mechanisms of hydrogen embrittlement in AM materials, the AM fabrication parameters and post-processing parameters of the AM parts can be designed to prevent hydrogen embrittlement,” Hickey comments.
“Then ultimately the possibilities and applications for these AM materials are even greater.”
The Connect Program
USTA and SwRI’s Connect Program is designed to enhance greater scientific collaboration between the two institutions, as well as increase both UTSA and SwRI’s research-funding base with cross-campus collaborative programs. It has been funded by a $125,000 grant from the Connecting through Research Partnerships (Connect) Program, a jointly-funded collaborative initiative between the two institutions.
As well as their investigation into the hydrogen embrittlement of additive manufactured metals, the two institutions have also collaborated to develop a 3D printed implant that can deliver a controlled medicine dosage over several weeks. The device could be used to help treat infections or provide ailment to patients suffering from things like arthritis, cancer or AIDS.
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Featured image shows oil drilling in an oil field. Photo via UTSA.