In the ever-evolving landscape of materials science, a groundbreaking discovery has emerged that could significantly impact the energy sector and beyond. Researchers at the Helmholtz-Zentrum Hereon in Geesthacht, Germany, have identified a critical phenomenon that could affect the safety and durability of welded joints in manufacturing processes. The culprit? Liquid metal embrittlement (LME) in solid-state welding, a finding that has never been reported before.
Liquid metal embrittlement occurs when a liquid metal penetrates the grain boundaries of a solid metal, causing it to become brittle and crack. This phenomenon has long been a concern in fusion welding, but its occurrence in solid-state welding processes was previously unknown. Now, a team led by Ting Chen from the Institute of Material and Process Design has observed LME in refill friction stir spot welding (refill FSSW) of magnesium (Mg) to galvanized steel. This discovery, published in Materials Research Letters, could have far-reaching implications for industries that rely on these materials and welding techniques.
The energy sector, in particular, stands to benefit or be challenged by this new understanding. Magnesium alloys are increasingly used in lightweight structures for energy-efficient transportation, while galvanized steel is a staple in infrastructure and renewable energy installations. The safety and longevity of welded joints in these applications are paramount, and the potential for LME adds a new layer of complexity.
“Our findings highlight the need for careful consideration of material combinations and welding parameters to prevent LME,” said Chen. “By understanding the mechanisms behind LME in solid-state welding, we can develop strategies to mitigate its effects and ensure the reliability of welded structures.”
The research team conducted microstructural characterization of the cracks formed during the welding process, revealing the telltale signs of LME: the penetration and enrichment of zinc (Zn) at the magnesium alloy grain boundaries and the formation of a liquefied phase. To validate their observations, they performed tensile tests on zinc-coated magnesium alloy at elevated temperatures, identifying the temperature range in which LME occurs.
But the story doesn’t end with the identification of the problem. Chen and her team also proposed and experimentally validated strategies to prevent LME. These strategies could pave the way for safer and more reliable welding practices in the energy sector and beyond.
As the energy sector continues to evolve, with a growing emphasis on lightweight, durable materials, this research could shape the future of welding technologies. By addressing the challenges posed by LME, industries can ensure the safety and longevity of their structures, ultimately contributing to a more sustainable and efficient energy landscape. The discovery of LME in solid-state welding is a testament to the power of materials science in driving innovation and progress. As we look to the future, this research serves as a reminder of the importance of understanding the fundamental processes that govern the behavior of materials.