MOSCOW, Russia / EuroWire.IO / – A groundbreaking ultrasonic welding technique developed by scientists from South Ural State University in Chelyabinsk, in collaboration with Chinese colleagues, has successfully doubled the strength of metal joints. This advancement also enhances the lifespan of welded parts by 1.9 times. The results, reported by TV BRICS and published in the journal Engineering Fracture Mechanics, focus on joints between dissimilar metals, such as steel and aluminium.
Difficulties in welding different metals have long posed challenges for engineers, primarily because brittle intermetallic layers tend to develop at the contact points. These layers are prone to cracking under stress, weakening the overall structure. The new ultrasonic spot welding method seeks to mitigate this issue. Spot welding remains a common technique for joining metal sheets in car bodies and other assemblies. The university emphasized that their findings have been documented in a recent publication.
The process involves the application of ultrasonic vibrations with a power of approximately 1,200 watts during welding. These vibrations help to refine the metal’s crystal structure within the weld zone, reducing crystal size by nearly five times. Instead of coarse crystals, the process produces small, uniform ones. Additionally, the method significantly decreases the thickness of the brittle intermetallic layers at the joint—by 50%—thereby strengthening the weld.
Ultrasound eliminates trapped air from welds
The ultrasonic waves also serve to expel air bubbles from the metal during the welding process. This results in denser welds with fewer internal flaws. Experimental results demonstrated that the joint strength was doubled using this technique, while the service life of the components increased by 90%, or 1.9 times. The researchers noted that these welds are more capable of withstanding prolonged vibrations and mechanical stresses without cracking. Such resistance to fatigue is particularly important for parts used in moving vehicles.
The university has not disclosed specific strength measurements or detailed testing parameters in its official statement. The improvements are expressed in relative terms. The team described their approach as a way to enhance the reliability of structures made from mixed metals. Combining steel and aluminium is a common strategy to reduce weight while maintaining strength, but weak joints have historically limited the effectiveness of such designs. This project was conducted in partnership with Chinese colleagues.
Implications for lighter vehicles, aircraft, and infrastructure
The researchers highlighted potential applications across the automotive, aerospace, and construction sectors. In automotive manufacturing, the technology could facilitate the joining of steel safety cages to aluminium doors, bonnets, and wings. Developing lighter hybrid structures might enable electric vehicles to achieve greater range on a single charge. In the aviation industry, lighter airframes could support more passengers or cargo, all while reducing fuel consumption. Weight reduction remains a critical objective in both industries.
In construction, this ultrasonic welding approach could be used for metal joints in bridges and high-rise buildings. The university suggested that such joints could outperform traditional monolithic concrete in terms of strength. The timing for the commercial adoption of this technology has not yet been announced. South Ural State University reported several applied research initiatives this year, emphasizing that this method could open new avenues for developing lighter, more durable structural components.