Hydrogen energy is one of the main directions for the development of new energy sources, but how to prevent hydrogen gas from attacking energy storage tanks during storage has become an urgent problem to solve. Recently, a university in Taiwan has successfully developed stainless steel materials that can resist hydrogen tunnel attack. If this material can be put into formal use, it will become an important milestone in the development of hydrogen energy.
Most of the hydrogen in the market is produced through water electrolysis and other chemical processes, with lower pollution levels compared to traditional fossil fuels. However, challenges such as easy explosion, low compression rates, and poor storage stability still need to be overcome. Currently, the main materials used for hydrogen storage tanks include metal, glass fiber, and carbon fiber, each with its own advantages and disadvantages.
Metal storage tanks are easily eroded by high-reactive and small particles of hydrogen gas, leading to hydrogen tunneling. This phenomenon can replace metal atoms, causing the entire metal storage tank to exhibit a phenomenon called “hydrogen embrittlement” during operation. This phenomenon is detrimental to hydrogen storage and can easily lead to safety issues.
Glass fiber storage tanks contain a large number of glass microspheres with diameters ranging from 25 to 500 microns. These glass microspheres can effectively trap hydrogen gas and prevent hydrogen tunneling. However, the drawback is the difficulty in manufacturing large quantities of high-strength hollow microspheres, and this storage tank also has characteristics of low hardness and susceptibility to impacts. Additionally, if these hooked micro glass beads enter the human lung, they not only cannot be expelled normally but also pose a risk of cancer.
Carbon fiber storage tanks use physical adsorption theory to store hydrogen, absorbing large amounts of hydrogen gas on the surface of carbon nanofibers. However, hydrogen gas easily reacts with carbon and escapes, resulting in significant loss of stored hydrogen gas. These challenges facing hydrogen storage have led to doubts about the development of hydrogen energy.
In this case, a professor from the Department of Materials Science and Engineering at National Taiwan University, led by Professor Hong Feiyi, successfully developed a “416B stainless steel” material that can resist hydrogen tunneling attacks, as well as a material called “420L stainless steel” for welding 416B stainless steel.
The team is currently applying for a patent, and numerous materials-related companies and news media have reported on this development.
In their research, they found that the 416 stainless steel used in military applications has the same corrosion resistance and rust resistance properties as 309 and 316 stainless steel, but with better strength and hardness. Therefore, they chose to improve 416 stainless steel by adding trace amounts of tantalum (Ta) and molybdenum (Mo) metals inside the 416 stainless steel, followed by heat treatment to turn the material into 416B stainless steel with a tough needle-like structure (interwoven crystalline structure).
The team conducted hydrogen tunnel resistance tests on 416B stainless steel. They shaped it into a dumbbell-like form and placed it in water for electrolysis to allow hydrogen gas to erode the middle region of the material. Then, they subjected the material to a hydrogen embrittlement test on a tensile fatigue testing machine to examine its hydrogen resistance properties. The testing principle is that if the material exhibits “hydrogen embrittlement,” metal fatigue and fracture are likely to occur during the short-duration tensile process.
The results showed that the hydrogen tunnel resistance ability of 416B stainless steel is over two times higher than other industrial-grade stainless steels, with superior strength and hardness compared to traditional stainless steel. Furthermore, they observed 416B stainless steel under an electron microscope and found a large number of interwoven crystalline structures, enabling it to resist prolonged attacks and displacement of hydrogen gas.
Additionally, since valves and pipelines for hydrogen storage require welding, the welded areas are especially susceptible to hydrogen attacks. Therefore, the team conducted complete dehydrogenation work on the original ordinary welding material “420 stainless steel,” turning it into the effective hydrogen corrosion-resistant “420L stainless steel.”
The results of this experiment have led the team to believe that 416B stainless steel and 420L stainless steel materials have the potential to be applied to hydrogen energy vehicles and hydrogen fuel transportation pipelines, preventing storage tanks, pipelines, and vehicles from causing hydrogen leakage or safety issues due to the “hydrogen embrittlement” problem.
Professor Hong Feiyi stated, “The characteristics of 416B stainless steel make it suitable for future application in equipment related to hydrogen storage, such as hydrogen-resistant valves, fasteners, and fittings, and it can also be used in hydrogen energy vehicles.”