Found in everything from kitchen appliances to sustainable energy infrastructure, stainless steels are used extensively due to their excellent corrosion (rusting) resistance. They're an important material in many industries, including manufacturing, transportation, oil and gas, nuclear power and chemical processing.
However, stainless steels can undergo a process called sensitization when subjected to a certain range of high temperatures—like during welding—and this substantially deteriorates their corrosion resistance. Left unchecked, corrosion can lead to cracking and structural failure.
"This is a major problem for stainless steels," says Kumar Sridharan, a professor of nuclear engineering and engineering physics and materials science and engineering at the University of Wisconsin–Madison. "When stainless steel gets corroded, components need to be replaced or remediated. This is an expensive process and causes extended downtime in industry."
Sridharan and Kasturi Narasimha Sasidhar, an assistant scientist in Sridharan's group, have demonstrated a new approach for restoring stainless steel's corrosion resistance that could be much faster and potentially less expensive than conventional high-heat remediation methods.
To fundamentally understand why their approach was so successful at restoring corrosion resistance, the researchers harnessed an advanced technique called atom probe tomography in collaboration with Madison-based company CAMECA Instruments Inc. (AMETEK), which has ties to UW–Madison.
The team detailed its findings in a paper published March 5, 2025, in the journal Metallurgical and Materials Transactions.
For their approach, the researchers used a technology called "ultrasonic nanocrystal surface modification" on a sample of sensitized stainless steel. In this process, a hard pin taps the steel's surface at extremely high frequencies.
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