MOSCOW, Russia / EuroWire.IO / – A collaborative effort between Russian and Chinese scientists has resulted in a novel ultrasonic welding method that doubles the tensile strength of metal connections. Additionally, this process increases the durability of welded parts by a factor of 1.9. Led by researchers from South Ural State University in Chelyabinsk, the project involved partners from China. The findings, reported by TV BRICS and published by the university, focus on welding joints between dissimilar metals like steel and aluminium with different properties.
Engineers have long faced difficulties when connecting different types of metals due to the formation of brittle intermetallic layers at the joint interface. These layers tend to crack under stress, compromising the overall integrity of the structure. The new ultrasonic welding approach aims to mitigate this issue during spot welding, a common technique used in assembling car bodies and similar structures. The university confirmed that the research was published in Engineering Fracture Mechanics.
By applying ultrasonic vibrations with a power close to 1,200 watts during the welding process, the method enhances the quality of the welds. These vibrations refine the internal crystal structure of the metal, with crystal sizes decreasing by nearly five times, resulting in smaller, more uniform grains instead of coarse ones. Moreover, the process reduces the brittle intermetallic layers at the joint by 50%, improving overall joint stability.
Ultrasound facilitates removal of trapped air bubbles within welds
The ultrasonic energy also helps eliminate trapped air bubbles inside the weld, leading to denser joints with fewer internal flaws. Testing demonstrated that the strength of the welded connections doubled using this technique, while the lifespan of the components increased by 90%, or 1.9 times. The scientists noted that these welds are better equipped to withstand extended vibration and mechanical loads without cracking, a crucial feature for parts in dynamic environments such as vehicles.
The university did not disclose exact strength measurements or detailed testing conditions in its announcement; instead, the improvements were expressed in relative terms. The researchers emphasized that their method offers a way to enhance the reliability of structures made from mixed metals. Combining steel and aluminium to reduce weight while maintaining strength has been limited by weak joints, but this new process could change that. The project was conducted jointly with Chinese collaborators.
Implications for lighter vehicles, aircraft, and infrastructure
The scientists indicated that this ultrasonic welding technology could see application in automotive, aerospace, and construction sectors. In the automotive industry, it might enable joining a steel safety cage to aluminium doors, bonnets, and wings. Such lighter hybrid structures could extend the driving range of electric vehicles. In aviation, reducing the weight of airframes could allow for increased passenger or cargo capacity, lowering fuel consumption. Weight reduction remains a primary objective for both industries.
In construction, the method could strengthen metal joints in bridges and skyscrapers, potentially surpassing the bond strength of monolithic concrete. The university has yet to specify when the technology might be adopted on an industrial scale. Several applied research projects are underway at South Ural State University this year, and they believe their method opens up new avenues for designing lighter, yet more robust, structures.