Hydrogen embrittlement, the degradation of metal by hydrogen gas, is one of the largest problems that will be facing the infrastructure of the United States over the next few decades. On October 11th, Dr. Ian M. Robertson of Oxford University, England gave a guest lecture about his research on the effects that hydrogen embrittlement will have on the United States.
To introduce his lecture topic, Robertson provided some background on why hydrogen will play such a key role in the future. Hydrogen is currently a forerunner in the search for a replacement for petroleum, which as Robertson said, “is not a limitless supply.”
Robertson’s lecture primarily focused on the challenges created by transporting hydrogen through the existing natural gas infrastructure. The current problem with the existing infrastructure is that the materials originally used in the construction of its fuel pipes are unknown, so it is a challenge to predict their interactions with hydrogen. Beyond this, hydrogen gas proves to be highly corrosive, so even the highest quality materials will be affected. This makes it extremely difficult to convert the old infrastructure for hydrogen use.
Dr. Robertson has spent the last 20 years researching the effect of hydrogen embrittlement on an assortment of metals. Although scientists have been aware of hydrogen embrittlement for over a century, they are still discovering the details.
“Hydrogen causes things to happen at a lower stress level than you would expect” said Robertson. For example, when nickel is exposed to hydrogen gas it fails in a granular fashion instead of a ductile fashion. The hydrogen wears down the nickel, which usually breaks from being bent back and forth multiple times, by causing it to be rubbed away.
Therefore, hydrogen enhances the mobility of dislocations within a metal and can cause a stationary crack to move at a constant stress. When a stress that the metal can normally withstand is applied, the metal may actually fail due to the presence of hydrogen.
The effects of hydrogen embrittlement are important to understand before existing gas lines can be used for hydrogen gas. If scientists do not adjust these lines, catastrophic failure may occur. In the eyes of Robertson, understanding the effects of hydrogen on the mechanical properties of metals is crucial to ensuring that alternative fuel, such as hydrogen, can power the transportation sector.