MOSCOW, Russia / EuroWire.IO / – The application of ultrasonic welding by scientists from Russia and China has resulted in metal joints with twice the strength and a 1.9-fold increase in service life. This breakthrough was accomplished through a collaborative effort led by researchers at South Ural State University in Chelyabinsk, with partners from China. The findings were highlighted by TV BRICS, citing the university. The innovative technique specifically targets joints between metals that exhibit different properties, such as steel and aluminium.
Creating reliable connections between dissimilar metals has historically posed significant challenges for engineers. Intermetallic layers tend to become brittle where the two materials meet, often cracking under stress and weakening the overall structure. The new ultrasonic welding method aims to mitigate this risk, especially during spot welding processes, which are commonly employed to join metal sheets in vehicle bodies and various assemblies. The university noted that their research was published in the journal Engineering Fracture Mechanics.
By integrating ultrasonic waves of approximately 1,200 watts into the spot welding process, the new approach enhances the quality of welds. The vibrations promote a refinement of the metal’s crystal structure within the joint, reducing the crystal size by nearly five times, resulting in a more uniform and finer grain. Additionally, this process cuts the thickness of brittle intermetallic layers at the joint by half, significantly improving the weld’s integrity.
Ultrasound eliminates trapped air within welds
The ultrasonic energy also expels air bubbles from the metal during welding, leading to denser joints with fewer internal flaws. Tests demonstrated that the strength of these welded joints doubled, while their lifespan increased by 90%, or 1.9 times. The researchers emphasized that such welds are more resilient against extended vibration and mechanical stress, preventing cracking. This enhanced fatigue resistance is especially vital for parts in moving vehicles.
While the university did not specify exact strength figures or detailed testing parameters, the improvements were expressed as relative gains. The researchers view this approach as a means to enhance the durability of structures composed of different metals. Combining steel and aluminium is common to reduce weight while maintaining strength, but weak joints have historically limited such applications. This research was conducted jointly with Chinese colleagues.
Potential impact on automotive, aerospace, and construction sectors
The team indicated that the ultrasonic welding technology could find uses across the automotive, aerospace, and construction industries. In vehicles, it could enable stronger connections between steel safety cages and aluminium components such as doors, bonnets, and wings. Lighter hybrid structures could facilitate longer driving ranges for electric cars. In aviation, reducing weight could allow aircraft to carry more passengers or cargo while consuming less fuel, addressing key sector goals.
In construction, the method might be employed to improve metal joints in bridges and skyscrapers, with the potential to outperform monolithic concrete in durability. The university has yet to specify when this technology might become commercially available. Several applied research projects are underway at South Ural State University this year, with the institution suggesting that this method opens new avenues for developing lighter yet stronger structural designs.