MOSCOW, Russia / EuroWire.IO / – A collaborative effort by researchers from Russia and China has resulted in an ultrasonic welding technique that enhances the tensile capacity of metal joints by 100%. This approach also prolongs the lifespan of welded parts by a factor of 1.9, according to findings reported by South Ural State University in Chelyabinsk, in partnership with Chinese colleagues. TV BRICS covered the study, citing the university. The method primarily addresses joints between dissimilar metals such as steel and aluminium.
Engineers have traditionally faced difficulties when joining different metals because brittle intermetallic layers tend to form at the interface, which can crack under stress and weaken the overall structure. The new technique aims to mitigate this issue during spot welding, a common process for joining metal sheets in car manufacturing and other applications. According to the university, the results have been published in the journal Engineering Fracture Mechanics.
This innovative approach incorporates ultrasonic waves with approximately 1,200 watts of power into the spot welding process, causing vibrations that refine the internal crystal structure of the metal within the weld. As per the university, this results in a nearly fivefold reduction in crystal size, producing smaller, more uniform crystals instead of coarse ones. Additionally, the method reduces the thickness of the brittle intermetallic layers at the joint by half.
Ultrasound Eliminates Air Pockets in Welds
The ultrasound also facilitates the removal of air bubbles during welding, creating denser welds with fewer internal flaws. Testing revealed that the strength of the joints doubled with this new technique, while the durability of the components increased by 90%, or 1.9 times. The researchers emphasized that these welds are better equipped to handle sustained vibration and mechanical loads without cracking, which is crucial for components in moving vehicles.
The university has not disclosed specific strength measurements or detailed testing parameters; instead, the improvements are presented in relative terms. The researchers view this method as a way to enhance the reliability of structures composed of mixed metals. Combining steel with aluminium is a common strategy to reduce weight while maintaining strength, but weak joints between the two have historically limited such designs. This research was conducted collaboratively with Chinese experts.
Potential Applications for Lighter Vehicles and Structures
According to the researchers, this technology could find use across the automotive, aerospace, and construction sectors. In vehicles, it could enable the joining of steel safety cages to aluminium doors, hoods, and wings, facilitating lighter hybrid designs that allow electric vehicles to travel longer distances on a single charge. In aviation, lighter airframes could carry more passengers or cargo while consuming less fuel, aligning with the industry’s weight reduction goals.
In construction, the method might be applied to metal joints in bridges and skyscrapers, potentially providing stronger connections than monolithic concrete. The university has not specified when this technology might be commercially available. Several applied research projects are underway at South Ural State University this year, and the institution asserts that this approach opens new avenues for creating lighter, more durable structures.