MOSCOW, Russia / EuroWire.IO / – Scientists from Russia and China have developed an ultrasonic welding technique that doubles the tensile strength of metal joints. This innovative method also increases the lifespan of welded parts by 1.9 times. The research was led by experts at South Ural State University in Chelyabinsk, in collaboration with Chinese colleagues. TV BRICS highlighted these findings, citing the university. The method specifically targets joints between metals with differing properties, such as steel and aluminium.
Achieving reliable connections between dissimilar metals has been a persistent challenge for engineers. The formation of brittle intermetallic layers at the contact points often results in cracks under stress, weakening the overall structure. The new approach aims to mitigate this issue during spot welding, a common technique used to join metal sheets in vehicle bodies and other assemblies. According to the university, these findings have been published in the journal Engineering Fracture Mechanics.
The process involves applying ultrasonic vibrations with approximately 1,200 watts of power during spot welding. These vibrations promote a refinement of the metal’s crystal structure within the weld zone. The university reports that the crystal size decreases nearly fivefold, resulting in smaller, more uniform crystals instead of coarse ones. Additionally, the process reduces the thickness of the brittle intermetallic layers at the joint by half.
Ultrasound eliminates trapped air within welds
The ultrasonic application also expels air bubbles from the molten metal during welding, leading to denser welds with fewer internal flaws. Tests demonstrated that the joint strength doubled using this method, and the service life of the components increased by 90%, or 1.9 times. The researchers noted that these welds are better equipped to resist extended vibration and mechanical loads without cracking. Such fatigue resistance is crucial for parts used in moving vehicles.
The university did not disclose specific strength measurements or detailed testing parameters in its statement. The improvements were described in relative terms. The scientists see this approach as a way to enhance the dependability of structures composed of mixed metals. Combining steel and aluminium is a common practice to reduce weight while maintaining strength, but weak joints have historically limited such designs. The research was conducted as a joint effort with Chinese colleagues.
Potential for lighter vehicles, aircraft, and infrastructure
According to the researchers, this ultrasonic welding technique could find applications in automotive, aerospace, and construction sectors. In vehicles, it might be used to connect a steel safety cage to aluminium doors, bonnets, and wings. Lighter hybrid structures could enable electric cars to achieve greater range per charge. In aviation, lighter airframes would allow more passengers or cargo to be carried with less fuel consumption. Reducing weight remains a primary objective in both industries.
In the construction industry, the method could reinforce metal joints in bridges and high-rise buildings. The university stated that such joints could outperform monolithic concrete in holding structures together. The timeline for industrial deployment has not yet been specified. South Ural State University has announced multiple applied research projects this year. The institution believes that this technique opens new opportunities for developing lighter and more durable structures.