MOSCOW, Russia / EuroWire.IO / – Researchers from Russia and China have pioneered an ultrasonic welding technique that effectively doubles the tensile strength of metal joints. This approach also prolongs the lifespan of welded parts by a factor of 1.9. The breakthrough was spearheaded by scientists at South Ural State University in Chelyabinsk, in collaboration with partners from China. The results, reported by TV BRICS and citing the university, focus on joints connecting dissimilar metals such as steel and aluminium, which present unique challenges.
Engineers have long struggled with joining different metals because of the tendency for brittle intermetallic layers to form at the contact points. These layers are prone to cracking under stress, compromising the overall integrity of the structure. The new ultrasonic welding method aims to mitigate this issue during spot welding, a process extensively used in fabricating car bodies and similar assemblies. The university announced that their findings have been published in the journal Engineering Fracture Mechanics.
The process involves integrating ultrasonic vibrations of roughly 1,200 watts into the traditional spot welding operation. These vibrations cause the crystal structure within the weld to become finer, reducing crystal size by nearly five times, resulting in a more uniform and smaller crystal formation. Moreover, this technique cuts the thickness of the brittle intermetallic layers at the joint by half, enhancing joint quality.
Ultrasound Eliminates Air Bubbles in Welds
The ultrasonic waves also serve to expel air bubbles from the metal during welding, leading to denser welds with fewer internal flaws. Testing revealed that the strength of the joints was doubled using this method, while the lifespan of the components increased by 90%, or 1.9 times. The researchers noted that these welds better resist sustained vibrations and mechanical stresses without cracking, an essential feature for parts used in moving vehicles.
The university has not disclosed specific strength figures or detailed testing parameters, reporting only relative improvements. The team described their approach as a way to enhance the reliability of structures made from mixed metals. Steel and aluminium are commonly combined to reduce weight while maintaining structural integrity, but weak joints have historically limited such applications. This research was conducted as a joint effort with Chinese colleagues.
Potential for Lighter Vehicles, Aircraft, and Infrastructure
The scientists believe this ultrasonic technique could be adopted across the automotive, aerospace, and construction sectors. In the automotive industry, it could facilitate the joining of steel safety cages to aluminium doors, bonnets, and wings. Such lighter hybrid structures might enable electric vehicles to achieve longer ranges on a single charge. In aviation, lighter airframes could support more passengers or cargo while consuming less fuel. Both industries prioritize weight reduction for efficiency and performance.
In the construction domain, this welding method could be employed for metal joints in bridges and skyscrapers, potentially providing stronger bonds than traditional monolithic concrete. The university has yet to specify when this technology might become commercially available. Several applied research projects have been announced by South Ural State University this year, with the university emphasizing that this method opens new pathways for creating lighter yet more durable structures.