Blending hydrogen with natural gas is a quick return strategy to reduce carbon emission. The use of pipeline steels has been considered as the most economically viable and industrially compatible technology for the distribution of hydrogen enriched gas at low pressures. However, the severe degradation of mechanical properties of steels due to the hydrogen embrittlement has remained a challenge facing the gas industry. Additionally, there is still no low-cost, high strength pipeline materials for hydrogen transmission in high pressure which can operate steadily and safely. This has significantly restricted the development of hydrogen economy.
Austenitic stainless steels have shown reasonable resistance to hydrogen embrittlement due to their face-centred cubic (FCC) crystal structure, which presents high hydrogen solubility and lower diffusion rate relative to other crystal structures. However, most common stainless-steel alloys lack the mechanical strength required for industrial gas transmission. In contrast, high strength low alloy steels meet cost-effectiveness, and high strength criteria but the embrittlement mechanisms in these steels are still not well understood. This project will deploy new techniques to address a key knowledge gap – how hydrogen affects the mechanical behaviour of specific microstructures in austenitic stainless and high strength low alloy steels. This will allow us to identify the mechanisms of embrittlement in these alloys and to design new alloy chemistries and microstructures to improve mechanical strength of austenitic stainless steels and to enhance hydrogen resistance of high strength low alloy steels.
Our team at the USyd has recently demonstrated breakthrough microscopy workflows that can observe hydrogen atoms distribution at nanometre length scales using Cryogenic atom probe tomography and to measure the deformation behaviour of specific microstructures in the presence of hydrogen by an in-situ micromechanical testing of hydrogen-charged samples in the electron microscope. We will identify the hydrogen embrittlement mechanism in the high strength low alloy and austenitic stainless steels, describing the hydrogen deformation response of different microstructural features. This obtained new knowledge will then be used to inform the predictive maintenance and development of new alloys resistant to hydrogen at POSCO, tailored for safe operation in hydrogen gas environment, including hydrogen enriched natural gas.
Project Leader: A/Prof Sima Yamini
Duration: 3 years